Just noticed here that https://picard.musicbrainz.org/docs/mappings/ says Picard is using TOAL for work, is this correct ?
In ID3 TOAL is described as:
The 'Original album/movie/show title' frame is intended for the title
of the original recording (or source of sound), if for example the
music in the file should be a cover of a previously released song.
whereas TIT1 is defined as:
The 'Content group description' frame is used if the sound belongs to
a larger category of sounds/music. For example, classical music is
often sorted in different musical sections (e.g. "Piano Concerto",
"Weather - Hurricane").
Now I know TIT1 is typically used for a type of genre grouping so I am not suggesting you should be writing to TIT1 but it is clear the ID3 spec didn't mean you to use TOAL either. Would make much sense to use TXXX:WORK since you use WORK for other audio formats. FWIW Jaikoz/SongKong also use TXXX:WORK although we only use it for Classical works rather than any work as that works better for our users, we have a separate field MUSICBRAINZ_WORK_COMPOSITION for any recording that is linked to a MusicBrainz work