this is probably the same thing as whatever is going on here: https://forum.inaturalist.org/t/join-project-translation-missing-rules-types-must-be-verifiable/28056.
This specific bug has been fixed, eg https://www.inaturalist.org/projects/geraniums-cranesbills-san-francisco-bay-area/join
So I’m going to close this report. Can’t currently test the other thread’s project due to this bug.