Why isn’t there a “Replace external tracks with local tracks” option?
Roon could even use downtime to do matching between the two so it would always use a local version if it’s available.
If you can search external databases for song versions, which Roon does, this shouldn’t be impossible.
This might also clear up the “This track is no longer available on Qobuz/Tidal”, by either deleting the track/album from our libraries, marking it clearly as unavailable, replacing it with a library copy, or segregating it to a special place in Roon where orphan tracks can be reviewed.