maybe the size is a misprint? Huge might work? or maybe the scale is a misprint and it's supposed to be 1sq= 10ft? or the room is supposed to be bigger without changing the rest of the map, there is room for it to be a bit bigger without moving it (5ft wider) or much bigger if it's moved east
I can confirm that doubling the size for the Under Fort Tempest Map (1 square = 10 ft) allows for multiple rooms (B5, B6, B10, etc.) to make waaaay more sense due to monster sizes. Really seems like a misprint. You can just say that the Kharnas and his angel army preferred giant doors, easier for angle wings to get through...