That looks as expected to me. When using Performer the role is in brackets "(role)". You need to use something else rather than round brackets
Oh, I never expected that. I have been used parentheses for annotating the name/title of non-native languages for years, rather than the role description.
Is that a common tagging rule for performer roles? Now I have understood there is a way to do so, however, I think it is good to have some flexibility on parentheses if possible.