Welcome to the Roon community, @patcoll.
Roon doesn’t use Mono any more. Not on Linux, macOS, or Windows. Mono isn’t needed to run Roon on Wine.
This has been a problem on and off for a couple of years now. Currently, I don’t have an issue with this. However, the app constantly crashes when switching between workspaces on Ubuntu 23.10 (Wayland.) Unfortunately, Roon on Wine isn’t a viable alternative to a native Linux app.
ARC (the subject of this proposal in Feature Suggestions) on the Linux desktop is very low on my list of priorities. Is this where your reply belongs? Maybe this thread is relevant?