The Core has two listings for Taschen’s Marvel Comics Library:
Marvel Comics Library: Fantastic Four &
Marvel Comics Library: Spider-Man
Under Spider-Man, there is a 1A for the regular and a 1B for the slipcase; there is no listing for the Spider-Man vol. 2. However, there is a #2 listed as the Avengers - no slipcase entry though.
Under FF, #3-5 are listed, correctly as Fantastic Four, X-Men, & Silver Surfer. No entries for the slipcase are provided.
My recommendation, for what it’s worth is to combine the two MCL entries into a single entry for “Marvel Comics Library” and list all of the current issues as they are: 1 = Spider-Man, vol. 1, 2 = Avengers, 3 = FF, 4 = X-Men, 5 = Silver Surfer, 6 = Spider-Man , vol. 2. And all entries need an A & B for the standard and slipcase editions.