Both presets still have some issues.
"Convert all artists with their roles after comma to performers" preset now writes performer tag with role properly. But it doesn't update display artist value. If you can't fix it, just remove the latter steps. I can use two separate presets myself.
"Sort performers by their roles" preset is now working. But it shows weird behavior for any performer with "mezzo-soprano vocals" role. It writes only that performer to artist tag with a value "008 performer name (mezzo-soprano vocals)". If I change the role to something else, it works.