Those should straight up not be allowed on the marketplace.
Solving the “Epic not properly curating the marketplace” problem would go a long way to simplifying the refund.
I think it’d be a good idea to throw some of the more solid members of the community a few bucks a month to handle curation. I’d be happy to take a few hours a week to properly vet submitted content for quality, liaise with the creators on how to get their work up to snuff, etc. A bunch of us doing that could definitely improve things. Probably easier and more viable than hiring full-time employees specifically for that job, and also a better alternative than some kind of Greenlight-esque crowdsourcing approach.