I ran into two things that confused me reading through the book and making the maps in Foundry. The first is in area A16 - the monster cages on the map are 5x5, but two of the cages are supposed to have large creatures in them and 2 of the cages are supposed to have huge creatures in them. Not sure how to handle that if the players open the cages and all of the sudden the monster triples in size. The two large creatures could be squeezing, but that doesn't really work for the two huge creatures.
Second, the variant devourer in area B29 - there is no information about what the variant is that makes the level 11 devourer into a level 9 creature, the weak template would only drop it to level 10. Also the book states that the creature is small, but the monster entry says: "Regardless of their original ancestry, devourers are always Large—fully 10 feet tall—as the remains of their mortal form strain to contain the evil within." So... what gives?