I have a number of courses for which I can find no way to contract the author/maintainer, and a few things I’d like to suggest as improvements/fixes. If the course owner no longer actively uses Memrise, and you’re a long-time user I would think it should be possible to have a button “Request contributor access”, and if the owner doesn’t block/query it within a short period (48 hours?), you can automatically be added as a contributor. The existing process for gaining contributor access doesn’t seem to be working at all as far as I can tell.
I’d even be OK if this was a premium-only feature (but I would hope I could remain as a contributor even if I chose not to continue the subscription indefinitely).