Roon does have on occasion some odd behavior regarding compilations; that was one of the first things I noticed when I started to try out Roon.
However, it is manageable. First, your CDs should be labelled accordingly, just like in the link Suedkiez provived (with the Metadata correctly assigning CD and track numbers).
And additionally, you can group tracks and tell Roon that an album is a compilation in the album editor
In the files. How did you rip the CDs? Your CD ripper should normally have ways to set this during ripping. Or you can use a metadata editor after ripping, there are many good ones like mp3tag or Yate on the Mac. Search the forum and you will find lots of discussions about metadata editors and also about correct tagging of multi-disc CDs.
I have already made the mistake when ripping with dBpoweram by not specifying the number of CDs current/CD total. With the 3 CD just now it worked perfectly with the correct specification.
Now I just have to repair the previous ones…,
I use MP3 Tag, maybe it works with that.
I should perhaps also clarify that I never actually edit the metadata in the files Roon has access to.
My setup is for a variety of reasons thus:
All my music is on a hard drive, for legacy reasons in ALAC format. I use iTunes and MP3Tag to curate the collection, any changes made to the music files are made to the files on that drive.
That music folder then is regularly mirrored to a backup drive and to the NAS drive. Roon is installed on the NAS and has only access to the files on the NAS drive. So the files are not actually edited ON the NAS drive, just periodically updated. And Roon recognizes these updates right away.
You could use SongKong to fix your previous ones. Unlike tools such as Yate or Mp3tag there is no need to fix them one by one you can do the whole lot in one go, you can try it in preview mode first to check the results are correct for you.