Just discovered this little gem...
When there's a failure for whatever reason to update/insert/change password/etc., Converge adds the request to a db table "api_queue" through $ipsclass->add_api_to_queue().
There is no code in all of Converge that I can find that then does something with this queue. You can't view or manage it from the ACP, and nowhere can I find any code that tries to reprocess the queued requests. They just sit there indefinitely.