Probably there are better ways of doing this, but I could suggest the following workflow with the given example:
Performer tag before:
Göteborgs Symfoniker (orchestra); Vladimir Chernov (baritone vocals); Sergej Larin (tenor vocals)
Custom Text:
soprano vocals; mezzo-soprano vocals; alto vocals; tenor vocals; baritone vocals; bass vocals; choir vocals; orchestra
Performer tag after:
Sergej Larin (tenor vocals); Vladimir Chernov (baritone vocals); Göteborgs Symfoniker (orchestra)
- assign a number to each role in custom list from 1: tenor gets 4, baritone 5, orchestra 8.
- substitute the role with the assigned number: Sergej Larin (4), etc.
- sort values by the numbered role in ascending order: Sergej Larin (4) will come first.
- substitute each number with its original role: Sergej Larin (4) becomes Sergej Larin (tenor vocals), etc.