Welcome!
Your DC sounds like a delightful, high-energy, creative young person.
The feedback you've received from your psych is thoughtful and nuanced, from what I can tell, and should be the best place to start from in terms of understanding the evaluation data.
A couple of general observations, trying not to duplicate too much of what you've already reported:
1. Perhaps you could elaborate a bit more on why you suspect autism. I am not seeing a clear pattern of that based on what you've reported. Some behaviors do align with ASD, such as sensory sensitivies, executive function issues, and some early anxiety, but the key feature is really social communication and interaction skills, and the only information we have on that is that she is incredibly social and craves social interaction, which, if anything, would be more likely to point us in the opposite direction (although individuals on the spectrum can be interested in social interaction as well). The item analysis from the WISC-V Comprehension subtest could suggest some relative impairments of this nature, but they might also be related to the gaps in cause-and-effect thinking that often occur in individuals with executive function disorders like ADHD. It's true that ASD and ADHD co-occur at a pretty high rate, but so far, there appears to be more data supportive of ADHD alone than of the two together.
2. The convergence insufficiency certainly seems like a reasonable explanation for much of the early reluctance to read. Even if decoding was not difficult, if reading involved prolonged eyestrain, I can imagine that it became an aversive activity. That emotional response to reading may not have entirely been overcome, except when text is highly-engaging. Her ongoing dysfluent reading may or may not be related to her reading history, since she has had less reading practice at this point than she would otherwise have had. I should note, too, that your perception of her oral reading fluency is probably in reference to what you already have experienced of her verbal cognition and oral fluency, since formal testing found her oral reading fluency on grade-level text to be at the top of the average range, bordering on above average. Not exactly delayed! But it -is- substantially lower than her oral word fluency, which was at the 98th %ile, a full standard deviation higher than her oral reading fluency. And it is clear from testing that, even when somewhat bored, she is able to apply phonics to sound out words quite well. So the skills are there, but perhaps applied only when forced to do so. That would suggest that the early reading behavior (in both languages) of guessing and skipping may have been attentional in origin.
3. Another reference check: it is actually not all that unusual for the oral language of two and three year olds to be unintelligible in unknown speech, as your DC's was. Toddler-speak is quite often perfectly understandable to the child's closest caregivers (often parents), while being quite unintelligible to everyone else. My takeaway from this would be that (as with handwriting), your DC's oral-motor skills were no more advanced than the next child's, despite very strong language skills, which made her oral language rich and complex, but comprehensible only to those familiar with its idiosyncrasies.
4. And a little anecdotal comment: some of your DC's profile feels very familiar (though not identical) to me, as one of ours was also a very active, creative, social young learner who far preferred inventing one's own to following someone else's design. We used tiny private schools that were willing to make some accommodation for the first several years (such as early entry, curriculum compacting by testing out of units or chapters in math, SSA, whole-grade skip, etc.) until the last TPS ran out of sufficiently advanced material (well, technically, they offered to completely individualize DC's academics) before DC ran out of grades at the school, and we decided to move to homeschooling. Our DC has many qualities which overlap with the diagnostic criteria for ADHD, but has never been diagnosed, and now functions quite well as a university student. Many of the most overt behaviors lessened every time we made an instructional adjustment for a better match, but they never went away entirely. We've consciously framed these qualities as "things to know about yourself", rather than deficits, but also managed them with frequent conversation, modeling and reinforcement regarding developing a broader repertoire of executive functions. After many years of intentional parenting on this, as well as DC's own choices and efforts, these underlying qualities are now more often charming and creative than disruptive or annoying (either to DC or to others).
In response to your specific questions:
1. vocabulary: Yes, that is likely the principal factor. I would also add that a child who has been in French immersion for the entire formal educational experience is not fully comparable to the norm group for this test (in either English or French; I assume the English version was administered). What is known about dual language learners is that there are some early lags compared to monolingual learners, but that long-term, they develop stronger metalinguistic/higher-level language skills.
2&3. lc/rc vs VC: There are a number of possible explanations for these, some of which are located in the learner, some of which reside in the instrument, and the principal one of which is simply statistical. If you are familiar with the concept of regression to the mean, that would be the first and simplest explanation. I can illustrate this with a rough ballpark calculation: most achievement tests have a correlation of about .6 with most cognitive measures. So an FSIQ of +2 SDs would predict achievement scores of about +1.2 SDs, which translates in her specific case to about 122--not too far off of nearly all of the obtained achievement scores, with the exception of SC and NO, which are just a bit higher than predicted (but within the range consistent with the FRI).
For LC, other factors may be related to attention/working memory particularly as it impacts the ODC component score. (Note that receptive vocabulary is up in the 90th %ile, while ODC is only the equivalent of about standard score 109.) Your next question, which I'll address here in the middle of this one, is about SR and DSF, and has relevance to ODC as well. All three tasks are quite sensitive to attention/working memory effects, and all ended up in the same range of performance (if we convert them all to standard scores: DSF 105, SR 101, ODC 109). When I see a profile where the DS subscores are stronger in the manipulation conditions (DSB & DSS) than in the rote memory condition (DSF), I wonder about attentional factors. And then we see confirmatory data on other tasks with significant attentional loads, such as the very similar sentence repetition task, which is also a verbatim auditory memory task. ODC, again, is presented entirely in the auditory mode, and allows for no repetitions, so it has even heavier auditory memory demands, but also has a little more space for compensating with higher-level cognition, since answering with the gist sometimes is enough.
There is one other outlier with regard to memory span, which is the picture span task, which scored more like the DS manipulation tasks, and may have benefited from having visual supports, whether because it helped with maintaining attention (and you note that she prefers books with pictures in them), or if visual memory is simply stronger in some ways. I am going to postulate that she may have preferred being read to when she was very young because all of the read-aloud books for that age have pictures in them. As a middle-grades child, read-aloud books are much less likely to have pictures in them, which doesn't allow her to compensate for whatever it is that affects auditory attention (dysregulated attention, auditory processing, etc.) with visual supports.
Many of the same arguments with regard to ODC and the possible impacts of dysregulated attention also apply to RC, as literal comprehension requires noticing the details, and inferential comprehension requires maintaining the thread all the way through the text, in order to make connections between information in different places. The types of text she enjoys reading are very high stimulation, and often plot-driven, rather than character-driven, which probably helps her to sustain attention long enough to enjoy the narrative progression, and also doesn't require her to pick up on subtleties to follow complex character development. In addition, though, the ceiling on RC is capped a bit by the item-set format. That is, all grade four students, regardless of strength, read the same passages (unless they are particularly challenged, in which case they might drop down to an earlier item set; but no one reads above grade-level sets). So earning an exceptionally high score on RC requires both making extremely few errors and providing sufficient elaboration on correct responses to obtain full credit.
4. school: you've already received some good insights from your psych, and your own observations sound quite reasonable to me. The only thought I think I would add to this is to consider following up a bit on the question of dysregulated attention and other executive functions. A learner who is significantly underchallenged (as your child appears to be) might quite reasonably present as inattentive or bored in school, but as we've discussed, there are also some aspects of her evaluation data that suggest there may be an underlying vulnerability in regulation of attention that is being amplified by her instructional mismatch. (e.g., ADHD)
In terms of homeschool vs institutional school, perhaps it would be worth having a conversation with DC regarding what exactly she likes and dislikes about school. On the one hand, she dislikes going to school. On the other hand, you have stated that homeschool is not an option because she is highly socially-motivated. But at some point, the attraction of school for social contacts may not be outweighed by the frustration of instructional mismatch (on top of an already stimulation-seeking brain). It may be that the tenuous balance you have been maintaining between the two is tipping. School is also not the only solution to social interaction (although it is very convenient). When we moved to homeschooling the DC I mentioned above, DC was not actually happy with it, because of the social aspect, but agreed to the switch because it was clear that instructionally, that was the best solution. We did what we could to maintain opportunities for satisfying social contacts in other ways (extracurriculars, faith community, homeschool coop/meetups, etc.). We even tried to maintain connections with the school for school-based social activities (field day, family events, school carnival). Possibly your school would allow something like this, with loose connections to afterschool clubs, attending school only for certain days, such as to participate in specials (art, gym, music, computer), etc. School vs homeschool doesn't necessarily have to be all or nothing. (And fwiw, years later, DC told us that it was the right decision.)
