Are any of your edits, play counts, appearing? Or does it appear that the server is treating the music it sees as new and different versions than the original server?
If you don’t properly disable and edit storage location after a restore to point to where the music lives then Roon will treat the storage as new files. I have restored countless times in 7-8 years it has had the odd issues identifying some albums more recently that had previously been matched due to some metadata oddness but everything else comes back as it was.
@george_samuel did you get your backup/restore problem fixed? I too am having problems restoring on Linux and am wondering if I am a ‘one-off’ or whether the problem is more widespread?