Currently it's not possible to write scripts that target a tag format. Picard's defaults mean that anybody using a mixed library of ID3, MP4(Apple), and VorbisComment will have mismatched fields. It's not possible to fix this in Picard because TaggerScript is applied to data downloaded from the MusicBrainz server.

For example, this doesn't produce expected output because Picard doesn't look at matched files:

$if($eq(%_extension%,mp3),
,
$set(NOTMP3,"I am not an MP3"))

$if($eq(%_extension%,m4a),
,
$set(NOTMP4,"I am not an M4A"))

$set(_isflac,$if($eq(%_extension%,flac),1,0))
$set(_isvorbis,$if($eq(%_extension%,ogg),1,%_isflac%))
$if($eq(1,%_isvorbis%),
,
$set(NOTVORBIS,"I am not a VorbisComment"%_isflac%%_isvorbis%))

Ideally, TaggerScript should instead by applied only to a file that has been "matched" and is sitting in the right pane. This would allow for individual files to receive different tags via scripting even if they were sitting in the same MusicBrainz track.