I actually abandoned SongKong because of this (and also having to reverse composer names). I did post-edit a few SongKong albums with mp3tag but then gave up. So, yes, maybe someone knows how to configure SongKong to stop this?
I’ve noticed that entries under Involved People works well but Musician Credits only work if the format is Performer=Barbra Streisand. If the entry is Lead Vocals=Barbra Streisand this renders as Barbra Streisand (Lead Vocals) in Roon.
My remedy is to move all entries to Involved People and keep guest vocals in Musician Credits in the format Performer=Barbra Streisand`. I do all of this using Yate.
This works, but it’s a lot of work. And then I find that Roon inevitably has multiple entries for Involved People that are either incorrect–equivalence issues, name format, spelling etc. It took me about two weeks to update 65 albums in my collection. It’s really not worth the effort. I’d rather spend my time doing something else.
Can I check what audio formats your files are in, regarding Involved People/Musicians Credits AFAIK they should be treated in the same way for ID3 format (as used by Wav, Aif, Dsf) by Roon, if not that seems wrong. I wonder if there is an ID3v23 versus ID3v24 issue, I will look at this in more detail as soon as I can.