Those animations are all made by CA and are in the vanilla game. Modders are just changing the DB entries to modify which animations are used when. For example, the Roman infantry movement animation and Triarii kneel animation were both made by CA (for example, the kneeling in defensive testudo or the way Roman soldiers move in combat), it's just that the database tables have been modified so the units use the animations in different circumstances.
If AE is implementing new animations, then the animation Petellius says he has created is the first truly new one in AE.
In terms of truly creating new animations, the only mod I know of that has properly overhauled them to a significant degree is this. I'm also aware than Medieval Kingdoms may be adding new animations to some degree.












