Right, so it would appear that HDTT make their own organisation of material - they do not make a straight correlation with album releases.
So then you have major work ahead of you if you want to use this material in Roon. Roon recognises album releases. If it can’t make a match with a known album or box set, it will fall back to relying on the metadata in the files, and group files in a folder into an unidentified (by Roon) “album”. In this situation, you need to have very good metadata if Roon is to make connections with artists (performers), composers and compositions.
So for example in the Stravinsky/Shostakovich album, your current artist field has “Ogdon, Wilbraham, ASMF - Marriner”. Roon won’t recognise this, you would need to have “John Ogdon, John Wilbraham, Academy of St Martin in the fields, Neville Marriner” as the metadata for Roon to make the necessary connections in your database.
You asked for recommendations for a metadata editor. A simple, but good, editor that many in the forum use is Mp3tag. There’s also Songkong, which uses acoustic matching to identify files. That may produce better results for less work from you for your collection. The developer of SongKong is active on the forum.