What I found is that when re-targeting animation, even to a skeleton almost exactly like UE4 default, the finders local translation and rotation seem to ever so slightly “move” while when observing the same bone in the default skeleton on non-re-targeted (but identical) animation, the bones do not “move” in local space. Besides the fingers being “mangled”…
Look at the translation and rotation numbers, they should be identical but are not, and in the new skeleton and re-targeted animation they shift every frame, only by extremely small amounts, I don’t know if this is a floating point error…