Thanks for the nice write-up.
Off-topic alert!
Which is IMO a mistake. Yes, all the names are on the cover, but there’s probably a reason why anybody except Harnoncourt and Bach are white on light blue. Most people would have to pick up the CD to be able to read „Pregardien“ … for this purpose it would make no difference if the artist were on the back, and not on the front cover. I’d just list the two prominent artists and be done with it – heed the spirit, not the letter of the guidelines!
That said, you could certainly find other releases where a very long %artist% is fully justified.