> we have a fake account type "AI creator" which we record

This is genius! The LLM is so dumb that it falls for the honeypot.

    > We also ask them to prove they are the author of their work through various time-tested mechanisms.

I would love to know more details, but it is not a good idea to share on a public platform. That said, if it is working for you, then hats off: You have found/developed a effective "defense in layers" strategy.