Yep, I read your first issue. I’m not party to how support are helping you, but boxsets are certainly an issue in Roon - it needs to be improved. I guessing, but perhaps the issue needs to be resolved by the metadata provider, not Roon?
I can only suggest looking at this topic:
Perhaps editing the metadata outside Roon will help make all of your boxset visible? In most cases it’s an longstanding issue with the metadata Roon receives from providers, and possibly for you, a few distinct album releases being within the boxset. In the case of classical, the distributors can’t even agree on an industry wide standard for metadata.
Sadly, only from your DM’s with Roon support. Roon should certainly have an issue/ticket management system.