There is a reason they are free-form text fields. There is also a track position which is always an ordinal number. For the “track number” you can go as wild as your source.
In this particular case, I’m not sure whether those are supposed to be track numbers. It’s just kinda weird overall.
I would probably just do A1, A2, etc (or 1.1, 1.2) because here these seem more like “supertitles” (what’s the opposite of subtitles?) than “track numbers”, but in theory there’s nothing blocking this. IIRC we had some release where the track numbers were a Fibonacci sequence or a list of primes something like that rather than 1, 2, 3… and if they were printed like “One”, “Two”, I also wouldn’t have anything against entering that.
As @reosarevok says these are more like “supertitles” than “track numbers”. Representing this kind of information in the database is difficult without [MBS-6680] Allow for different sections in a medium
This has nothing to do with track number and medium section, it is just track title. The list of works that follows can be considered as the subtitle. Just like composers usually matter more than performers in classical music, dances usually matter as much as (if not more than) works in traditional music.
When you put it that way, from the viewpoint of those who dance to this release, we could be throwing away the most important part of the metadata.
Are you suggesting that
5 Hornpipes: The Showmans Fancy/Off to California
6 Jigs: Sweet Biddy Daly/The Humor’s of Whiskey/A Visit to Ireland
is the way to number and name the tracks?
I suggest Hornpipes: The Showmans Fancy/Off to California for the track title.
That’s how I would do it, though as @yvanzo said I would probably also use the A/B side indication but that’s not really part of this particular question.
Remember to do space-slash-space to separate the sub titles/works, so “Hornpipes: The Showmans Fancy / Off to California”.