hi,
the only thing I could see can go wrong is when you look in other direction then forward during avatar calibration but it was rather related to legs angle, not hands.
additionally when I played recently vrchat I noted that hand pose does not matter at all and there was actually no need to make each on a side like T letter.
perhaps you can record short video? but this might be rather topic to look for support on vrchat forum if all looks fine in steamvr.