Rather than crap on the Roon thread any further
I’ve had a wee look - it’s basically freeware written by one guy in the UK.
I’ve installed it without letting it at my data and it looks like a more modern, less abandoned MediaMonkey.
So now (I think) I’m letting it at the music. I’ve done a last minute in-case-of-catastrofuck backup, kicked off a scan and it reckons it’s indexed 7,400 of 26,040 files.
It remains to be seen what kind of a horse’s ass it makes of things.
Having used MediaMonkey probably for over 10 years I may have difficulty adjusting.