Its worth noting that Artist Credit Import only works for Roon 1.7 not 1.6, so you may have to get Roon to rescan?
But I think you are just talking about SongKong here and simply find and replacing () with  rather than using the fix. We dont currently have Find and Replace and the IPLS/TIPL/TMCL fields are not currently available in Manual Edit either.
The best I can think of is to add all fields to Format:Never Modify or Add these Fields except Performer and rerun Fix Songs, then apart from possibly matching some songs that were not matched before it should only update the Performer field and nothing else. But it will completely replace the Performer field so I suggest you try it out on a single album folder..