MusicBrainz stylke guidelines mean that featured artists should no longer be in the title, however in many cases they still are.
Since When tracks contains featured artists is set to Add all contributing artists to the artist field
and When albums contains featured album artists is set to Add all contributing album artists to the album artist field then when matching to MusicBrainz it always adds them as seperate artists in the Artists or AlbumArtists field
And since you have added Artist and Album Artist to Save multiple values as separate fields then it should store as multiple artists here as well.
But it will not currently remove from title them if found in title
Possible workaround is add Title field to Only Modify If Empty. or use Scripter task or Auto Edit/FInd and Replace task afterwards to search and replace in Title field
Confused about your screenshot because when I look at your Fix Songs spreadsheet I see the Artist field as required, the only issue is the Title field