I would agree that decoding at this level can be mostly a visual skill, and that her excellent spelling may be due to her equally excellent memory.
Yes, general knowledge can be affected by environmental exposure, though the WPPSI is less academic in its expectations, since many of the members of the norm group were not in academic environments. And she did not do that much better on Comprehension, which relies more on everyday experience than academic instruction. I still have to wonder about a potential real relative weakness in language-related cognition, because the pattern is consistent.
It is good, though, that there is currently no apparent academic impact on her fundamental reading and writing skills.
