Yeah, I liked to do that sort of thing all the time, but never thought about checking for drawn map references outside the clored boxes locations. You know that this same exact area is where you fight the Werewolf in Rondo too right? Also one room earlier is where you fight the Giant Bat boss.
The castle reshapes itself but like to keep some important areas (outside of story, its just devs paying homages, sure lol). I had compared CV1's map with SotN's one time and its pretty interesting, because the locations are there but scattered in some parts. Also CV1 level 2 appears in SotN, it starts one room after Death (climb stairs) and starts going left (to Alchemy Laboratory until you enter Royal Chapel and fights Medusa). The strange part is that in CV1 time this mini tower near Death seemed to resemble more Outer Wall because of its enemy placement.
This thread is really interesting.