I may have stumbled on an easy way to edit faulty metadata.
Before moving album file into Roon folder, add it to iTunes if you have it. There you right click on album and get “Album info” change all or any information, it is then saved to the original folder, within iTunes library. The same applies to all tracks, same process for tracks of course. Once completed copy and paste original file from iTunes, to Roon music folder.
I’ve done this four or five times now and each time the metadata showing in Roon is mine as changed. A quick look at the files on my MacBook Pro confirm my changes.
Of course this assumes the files in question are AIFF, ALAC or WAV. I’m not sure that iTunes will even recognise FLAC let alone allow editing. I could be wrong, I’ve been wrong before.
It’s quite easy to edit in DBpowerAmp ripper too and album is saved with your changes.