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 Feedback > 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?