I realized that fixing the animations is NEVER going to be finished for all of them, and even if it was, it would break all other peds. So I started looking through the models and skeletons, and tried just changing the bad bones' IDs to ones that aren't used in any animation. And it actually worked.
It's nowhere near perfect, but it looks good in every animation (except shooting, seems to be bugged)
I made 2 versions, one where only the rotation is fixed, and another where abnormal leaning is also fixed (which seems to cause more problems with shooting)
Get it here (IV characters only)