Sounds good, I’ll give it a try. Only potential problem is that it attracts a false positive risk, as the record could be months old and a total red herring for any present issues.
Edit: I’ve added the checker to look for records in the form of _acme-challenge.$requestedDomain.$requestedDomain and also _acme-challenge.$requestedDomain.$registeredDomain. It reports it at WARNING severity and tries to advise the user on the correct way to enter records. Ironically it was a pain in the ass to get Cloudflare to accept these erroneous records, if I clicked on the UI too much it would fix my mistakes 
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