She’s in MusicBrainz, so in all likelyhood, she’s in Roon. Maybe try to run your files in Picard to see if that helps. If that fails, another possibility is that there’s some bug somewhere with è, é, and e, so that’d be something to bring up with Roon Support.
You don’t need to (see above), but general rule for metadata issues: if it’s so unbearable that you feel the urge to complain so that someone else fixes it for you, it’s generally less effort to make a musicbrainz account and fix it yourself.