It's not a mistake, it's the change of stat block format since the Monster Manual was printed. "Angel" is no longer a valid subtype.The other Angel stat blocks have it, so it just feels like a sloppy mistake.
It's an adventure book, and was always advertised as such. It was never going to be a setting book, especially not one with fourteen different settings in it. If you didn't want a book of adventures you shouldn't have preordered it in the first place.And I think a setting book should have been done, then the adventures in a seperate book.