Hello! It would seem like I had skeleton_ functions excluded from automatic exposure to GMLive.
I'm honestly not entirely sure why, might have been some sort of issue with GMS1 (which wouldn't let you compile a game with mentions of skeleton functions without Pro edition).
I'll take a look at that for the next release but meanwhile you can workaround this by making small wrapper scripts, e.g.
/// skeleton_bone_state_get_w return skeleton_bone_state_get(argument0, argument1)
and then calling those when working with them from GMLive-enabled code.