Don’t put the # sign in there. That is a USA thing and not world wide. The Wikipedia page is neat and tidy, but your suggestion is very messy to read. Even worse in the second one where you write part 1, part 1.
The style guide says to use the text as the covers show. The trouble is the rear covers don’t actually match the way the tracks are broken down on the actual CDs. So there is no tracklist as the guidelines expect.
To try and answer your questions:
1\ Are they still producing these? The Wikipedia solution is neat and readable. There is no need for extra zero padding as they are human readable. If you need to adjust this for tagging purposes then tweak it in Picard and not the database. More importantly it is naming scheme the company uses to sell these on iTunes.
2\ It sounds like the Release Title should be Volume 1: The Adventure Begins. I see it written like that on the rear and I guess this is what the spine shows. Can you scan the cover in more detail so we can see these spines? Are there booklets with these?
(On a side note, you also should not be naming the separate CDs disc 1, disc 2, disc 3 as this is also against style guide and someone will come along and delete those bits)
3\ Wikipedia also covers the part 1, part 2 of those releases as they use 052a 052b etc. Much more importantly the Digital releases on iTunes use the 052a 052b naming.
If you must add numbering then use the iTunes releases as a guide for the names. That can then be argued as reasonable.
On the iTunes example of the disk you are quoting: https://music.apple.com/us/album/01-the-adventure-begins/559939816 the numbering stays fairly clear. BUT you seem to show that the CDs are broken up in to more parts than the Digital release?
The more I look at these the more I think that you cannot rename them in any sensible way. It is hard to even make them match the style guide as the track list doesn’t actually match the tracks on the CD!
The trouble with stuff like this it gets repackaged and resold so many times that numbering fails to make sense. They repackage it cheaply so the track names don’t match the actual tracks. If you add too many made up numbers to it then the re-issues are harder to link by name.
I am NOT a style guru so other people need to comment. I tend to use a bit of “common sense” when reading the guidelines. I can see how the digital track titles could give an reason to add the episode numbers as the artist sees them. But as the CDs themselves don’t actually have a track list then some imagination will have to be used here.
We need to work on specific examples, and try and match the CDs to the iTunes releases as close as possible.
I see a compromise would be to use the iTunes versions as a master, and then add Part x to the end of each. But use your neater roman numeral solution as you have currently entered them.
5 017: A Member of the Family I, Part 1
6 017: A Member of the Family I, Part 2
7 017: A Member of the Family I, Part 3
8 018: A Member of the Family II, Part 1
9 018: A Member of the Family II, Part 2
10 018: A Member of the Family II, Part 3
11 018a: BONUS! Paul McCusker Talks About Whit’s Family