Getting AI to perform animations can be tricky at the best of times, especially crouching, and may involve the use of "brute force" techniques such as
disabling AI (move and/or target) and
setUnitPos.
In OFP disabling AI is non-reversible, so if the characters need to act normally after completing the animation, you can use duplicate characters - one to do the animation and the other to continue the cutscene normally.
If this is
not for a cutscene and instead for in-mission action, I'm not sure what else to suggest.