The majority of my colleges are on Coalition but I have some on CommonApp so I have to use both. However, I don’t like any of the essay prompts on Coalition. Is it typically frowned upon to use a CommonApp prompt for Coalition’s “choose a topic of your choice” prompt?
Nope!
Choose a topic of your own choice means just that. If you have an essay you love, use it. Don’t make life harder then it needs to be.