Player Head Incompatabilities
I am not sure what exactly the cause is, and it is likely more to do with how the person who created the emotes configured the resource pack over the plugin -- but when you have custom HeadDatabase Heads placed next to one another they re-skin themselves into new textures. This persists when you delete the /models/player_head.json file... I've just reverted my project's back entirely, but this should still be addressed.