Usually when standing or sneaking, the punch/item use animation results in the arm smoothly reverting to its default position. This doesn't seem to happen when crawling (yet to test if this is a vanilla issue or a problem with the crawling animation the mod adds), in which the arm immediately shifts back to its default position rather than smoothly going back.

Did the test, rotates really fast all over the place, won't fix^^.

Currently "crawling"(technically swimming) is excluded from the animation smoothing. I'll have to test what this might cause.