To my experience, it is rarely on the cover (*).
It is sometimes on spine and, often on some (removable) sticker (sticker and/or obi for 初回限定盤 and the likes), and, more than often, nowhere at all — probably for my second hand stuff, for which no sticker is left.
Thus the comment rather than the title.
So I hadn’t thought about the cases where it is clearly part of the front cover, actually.
If it’s part of the title, as they usually don’t print those rounded brackets, it means that we should use the Style/Titles/Subtitles, which IMO does not look very good (at least for those edition texts).
(*) Well, rarely on the cover but it seems not. I found two examples from my collection where, well, I did probably not give justice to the front cover text.
MACHINE HEAD (25th anniversary edition)
Although, on the cover I do see many many stuff like:
remastered album · single · quadrophonic mixes
ANNIVERSARY 2CD EDITION
unissued (sic) quitar (sic) solos · remixes · 28 page booklet
True that I stripped down all that, I found it was too much of general and sometimes redundant (2CD) information rather than proper version name. So I took instead what often contains the best fit titles, the spine but put that version info (25th anniversary edition) as comment.
made in japan (the remastered edition)
This time I took the edition info from front cover and put it in comment instead of I should probably had to put it in title as
made in japan: the remastered edition with Style/Titles/Subtitles → with Style/Titles/Subtitles plus Style/Language/English.
Actually it’s not that rare that it’s printed on front, you’re right @Yvanz. I found some others as well in my collection.
But Catch A Fire (DELUXE Edtiion) where we can see that (removable) transparent plastic kind of obi.
So once disposed of, you cannot see that version name any more.
To avoid all those discrepancies and version name adaptations (removing 2CD and other bogus info), I’ve liked and used the idea of putting all those (for me) non title version info in comment.
But it’s true that on the other hand, I like verbatim copy.
We all have our contradictions.