Yeah, it's fun, though I believe it is incorrect when it says "Structurally, the house was constructed around a large central tower that contained an attic room." But given the way the tower moved around, maybe the house was indeed originally constructed around the tower but then the tower got bored and went walkabout.
Also, perhaps the greenhouse should have been included in the list of buildings on the Collinwood grounds. I don't think we ever saw it, but Roger mentioned it early in the series, as one of the buildings to be seen to when a storm was coming.