I believe that this is the expected behavior here, but I’m going to double-check with the technical team. I will be sure to let you know once I hear back.
I just double checked with the technical team and can confirm that this is the current expected Roon behavior. Roon has a two-way sync with TIDAL and any items you add to your Roon library will also be favorited in the TIDAL app.
This behavior might change in the future, but I can’t say when or if this change will occur. The best way to note your interest would be by submitting a feature request and get feedback from the Community.