Is Roon viable for classical music?

These actions are almost certainly going to cause you problems. Roon will have extreme difficulty in being able to identify albums and releases known to it.

For a start, Roon will recognise an album where a folder contains the complete list of tracks that the album has/had. By splitting up albums into folders containing individual works, you’re going to end up with a bunch of unidentified albums, each containing individual tracks, because Roon won’t have sufficient information to reconstruct the compositions from it (e.g. a symphony with four movements). Roon also looks at ID3 metadata tags, and if you’ve swapped the content of the Artist and Composer tags, Roon will probably fail to make much sense of it.

Give it a go, by all means, but I doubt that you’ll have a seamless import experience. As the Irishman said to the stranger who asked him the way to Tipperary, “if I were you, I wouldn’t start from here…”.