Your information on compound colliders was just what I needed!
Because I'm using Smooth Moves 2D animation, which recreates animation children when you run the game, I can't attach FSMs on animation children. Maybe one day Smooth Moves will allow these, but for now, I have to improvise.
So, this is what I did:
-Trigger event to check for collision with compound collider
-Get Name to check for when the bone inside the animation is hit. (Note to any Smooth Moves people: you have to have collision on the root and the bone.)
-String Compare to see if the bone collider has hit the other object.
Another note:
Because a bone is inside at least two layers of parents, you'll need to use Get Parent at least twice to traverse up to the parent animation.