I was watching this video by forgotten weapons and when he started talking about the magazine I noticed that he said that the MKb 42 (W) had a magazine bolt hold open feature:
This means that the bolt should not be closed when the last shot is fired, but should be held open. And when reloading, you change the mag and then merely tug on the bolt like on the Soviet semi-autos in the game.
One could excuse the current set up by saying it’s using StG-44 mags. Which, while compatible, did not have the hold open tab characteristic of the MKb 42 (W) mags. Meaning if the animations were to be changed, then the mag pool would have to change alongside it.