Put an optional email in the in-app feedback form. It’s non-trivial to tie up the email communication with Radicle, but the centralized/distributed nature of the system doesn’t alter the problem in a major way: the in-app feedback is basically interacting with backend server that interacts with a well-known Radicle node (probably on the same VM) that create/update issue on the behalf of the app user.
With that knowledge level, I guess you’re dealing with a very niche domain where you want feedback from sophisticated user that know about the domain, but might be programming illiterate. I think email based communication would closes the gap.