Thanks for the heads up! I'll try to adjust to level so this doesn't happen, or ensure you can still move horizontally when "pinned" in such a way.
The skulls don’t fall when the floor breaks because that’s what makes it challenging, but if I had used other enemies, ones that obey gravity, they would indeed falls.
The butterfly isn’t required for completing the last room, or any room, its an assist option that you can use solo or with a partner.