ask the creator of original mod, maybe he will ask and i'll update this mod.

i do not know, i checked only with zombies (alas, i could not help give them weapons to combine soldiers, they cannot pick up), the citizen attacked with SMG1 on zombie and the animations were all ok. i do not know what kind of problem you have. i'm don't know how to fix this, i'm sorry.

for hitscan weapons, yeah it affects where stuff like the head or arms or legs are positioned
since the server will still compute that based on the vanilla animations, and it does deal varying damage depending on that (including outright missing shots with the revolver for example due to it)
it does magnetize a little bit but overall yeah it does desync that

animation doesn't affect hitboxes

fyi: hitboxes will desync compared to the server due to the differing animations

oh thanks for noticing, i'll fix that

why is the link flagged as malicious? did you link the wrong thing or are you intentionally trying to do something malicious