I'm not surprised he's good at math, given his FRI and WMI, which are generally the best predictors of math achievement. In his case, the effect would probably be more focused on the face reading, and maybe, eventually, in geometry (but maybe not, since his fluid reasoning is so strong, and his spatial abilities aren't really weak, just relatively so).
And the NVI is of course quite strong, but we are really speaking of relative weaknesses here, not absolute ones. (And remember that two of the contributing subtest scores are the 19s from FR.) His NVI is also ten points lower than his VCI (which may well be an underestimate), and may be even more discrepant from the Extended VCI.
You do not need to do any additional testing to compute the extended index scores, if the examiner followed standardized administration procedures. All you need is the raw scores from the five subtests that reached max scaled scores. And the norm tables, of course, but your evaluator has those (they're also freely downloadable from the publisher's website, but I'd recommend having a qualified person doublecheck the conversions, and whether the recalculated scores are meaningfully different).
It's a lot harder to reach automaticity in handwriting than in typing. Wider range of complex fine motor skills. And a lot of extra initiations and placements, for every word when using cursive, and for every letter when using manuscript. That can be tough for learners with relative weaknesses in visual spatial skills, automaticity (represented here potentially by the relative weakness in PSI), organization or some combination thereof. Fortunately, it really doesn't matter much anymore, in the real world. Type away!
