Hey RowelCaps, welcome back to the forums!
As far as I know the fingers and hands have a lot of extra bones in the UE5 models, which can really make UE4 skeletons weird since they have no idea what to do once they have these extra bones!
I know with this thread the poster had a similar issue with their hands. Try watching the video through their link they posted and see if that helps you figure it out! Keyframing Animation Assets to Match Movement
The link was here in the first post:
