I am not the plugin's original author, I am mostly helping out with the webgl rendering side and fixing bugs. So, generally, I will not be doing work to add a lot more ACEs. I think the original author has moved on from using this plugin themselves, so I think it will likely stay with a minimal number of ACEs to support playing animations.
That being said if you have a few critical ACEs required, you can make a request up on the github website in the issue list:
github.com/gritsenko/c3_spine_plugin/issues
Also, since this is all done in JS, you can also use JS script in events to access the Spine API directly in C3.