I've used bullets in other stuff I've made with decent success. I've also done similar things to what I describe here by throwing an extra text box in the left margin, which is tragic and wrong, but gets the job done.
I called this a regression bug because it clearly used to be allowed and the use case for allowing it hasn't changed - since I downloaded this template, I'm clearly not the only person who finds the idea useful. Lacking other ways to bust out of the frame, this will do in a pinch.
I am not close enough to the product team to know why a hard limit of 100% would be desirable. It might just be that the "% object" was re-built with 100% as a default to solve some other issue, and this instance is inheriting it now, when before it was not limited that way. I'm a software product owner myself, and I know that if nobody speaks up, the features don't change, so I thought I'd bring up my specific use case and ask for the limit to be raised again.