As far as I'm aware, there are no canon layouts for any of the Druchii fortresses. I would, however, say that it needs to complex - just started reading the Malus books, and it describes the Drachau's palace in Hag Graef as expansive, and bewilderingly complex. Servants get sent in there and aren't found for days/ever.
It's due to the fact that slaves who can build - such as dwarves - are few and far between, and expensive when they can be found, so the elves just let one part of the city/palace/etc fall apart and then build on top of it!