Should this raise some sort of warning/error/indication if there is a configuration mismatch that can't be reconciled because there are messages in a queue?

It's not entirely obvious what response the API gives in the event of being unable to delete a queue - I'll investigate what happens...

It looks like DELETE if-empty is not supported by quorum queues:

$ curl --silent -u admin:password -X DELETE http://rabbitmq.example.com:15672/api/queues/zocalo/processing_recipe?if-empty=true
{"error":"bad_request","reason":"cannot delete queue 'processing_recipe' in vhost 'zocalo'. queue.delete operations with if-empty flag set are not supported by quorum queues"}

And this line should probably be:

self.delete(endpoint, params={"if-unused": if_unused, "if-empty": if_empty})