Thanks so much for your detailed response. I will continue to post here if/when I notice issues.
By the way, I downloaded the yml files and used AI to collate the English and Japanese in CSV files so that I could compare more easily. Doing it that way didn’t reveal problems; I quit reviewing after about 10 minutes or so when I realized that the number of translations is huge and, when viewed out of context, problems are very hard to find. The problems I DID find are with views that a user is likely to encounter early in the process of signing up for and getting acquainted with the interface. Even though a huge volume of very good work has been done, such problems coming up in basic views (user profile page, etc.) may lead users to underrate the overall quality of the Japanese interface (which is what I did initially). So, I hope that such views can be given priority when a new version of the platform is prepared.