As far as I can tell, these aren’t documented anywhere. I think REGISTRATION_RATELIMIT is relevant to the issue you hit. I think RATELIMIT_RATE applies to OAuth.
It was working with RATELIMIT_ENABLE
I tried to remove the flag before setting the keys you mentioned @pdpinch but to my surprise it worked even without it.
Must’ve been some other misconfiguration somewhere else. ¯\_(ツ)_/¯