Correct, if you update the local tags within your files, tagging/updating them with musicbrainz or some other tool then when you plex dance the system to try an match them. Also, remember tagging is only part of this, you need to also follow naming rules.
So, for example Lady Gaga and the album Joker - Folie a deux (Release group “Joker: Folie à deux: Music From the Motion Picture” by Phoenix & Gaga - MusicBrainz). If you put this album in a folder called \Lady Gaga\Joker - Folie a deux (2024) plex WILL NOT MATCH IT and it’ll be unmatched when scanned into plex.
Reason being that the first artist listed is Joaquin Phoenix (Joaquin Phoenix - MusicBrainz) so for auto matching to work it would need to be in \Joaquin Phoenix\Joker - Folie a deux (2024). You can of course manually match it but for auto matching it will not and its just something to be aware of.
I’m not aware of any way to match local plex guids with actual matched plex guids however maybe someone else from the community knows how. Manually fixing these up would be a nightmare and not practical.
If it was me and I was in your situation, I’d get the tagging right and naming right, then plex dance everything, ensure they are all matched and then create your playlists/rating again. Lot of work yes but its the only way if you want the content matched.
