Ah I thought that was the main motivation behind this mod? As I've seen xbox model conversions before without the animations and the reasoning was always that gta3 didn't support bone animations.
I guess the benefit for pedestrians (that don't have the new hands, as they were only added to major CS characters) is that they no longer have dodgy "joints". Although this is also a downside as it disables the limb detachment. Swings and roundabouts I guess.
From you saying it is a lot of work to add these animations, I assume then, that it is far more complicated than converting the Xbox / mobile animation file format to something the pc bone system you have created can read?
I would strongly disagree that it isn't noticeable. https://youtu.be/CnqNfThB96M?t=359
(Sorry, I couldn't find a video of just cutscenes from the xbox or mobile versions - there are no doubt better cutscenes to display the animations but this is the first one I found. There is the playlist in the sidebar for more anyway).
Go back and play the xbox version (or I assume also the mobile ones, though I haven't played those) and you will see it adds quite a bit of life to the cutscenes.
Particularly when the hands are in such a strange and awkward "claw" pose by default.
Anyway, it's your mod, and I appreciate any work people do to try and improve the game.
Thanks for all your time and effort!