Sorry a bit late busy sunbathing
The CD01 - Annotation is well known
Roon works on albums, so if you think of a box set as an album it will have CD01…CDxx
If annotated Roon will see each cd as an album and split them off. If you multi select them , right click first, shift click the last then Edit>Merge ronnwill reconstruct the Box
Box sets are badly handled , look at the Classical Consolidated thread for info, Roon is well aware of the shortfall alas …