Edit: I was wrong, RegisterForAnimationEvents "arrowrelease" will work for bolts.
It would not work for me at first because my conditions for bows stopped the script. So crossbows are NOT included in weapontype == 7. The are number 12.

Still....

Is it possible that a new set of RegisterForAnimationEvents were made for skyrim 1.7 but nobody has discovered them yet? I am wondering if there is a bunch more RegisterForAnimationEvents or new getAnimationVariableBool("") or new getAnimationVariableint("") or new getAnimationVariableFLOAT("") ?