You’ll need to have either Tidal/Qobuz connected to your Roon account and your success will depend on whether the tracks in your playlist can be found on Tidal/Qobuz.
Import the .csv into Soundiz (see instructions) and then within Soundiz sync the new playlist across to your Tidal/Qobuz account. You might want to note down any tracks it can’t find.
Then go to Preferences → Services → click ‘Edit’ next to Tidal/Qobuz → click ‘Sync Library now’ to sync Tidal/Qobuz with Roon. Alternatively you can just wait for Roon to do this automatically.
You should now see your playlist on Roon. But you can’t edit it within Roon. If you want to do that you’ll need to click the three dots (…) next to the playlist and select ‘Save a local copy’.
If you’re happy with your playlist being made up of tracks from Tidal/Qobuz you’re done, if you want to replace the Tidal/Qobuz versions with local FLAC files you’ll need to do that manually, one track at a time.