As an example, see Atavista (white cover), it is my tidal collection, if I got to it there is no way in roon to remove it, just to add it (but it is already saved or in the library). Am I misunderstanding something?
Yes. The Tidal view you are using is a direct look at Tidal, not, your library. So, when you add an album from that screen to your library, it will create a new album object in your local database, aka library, but that page is still looking at Tidal who knows nothing about Roon’s library…