Vesuvia had already revealed some inconsistencies with the ninth floor's structure. The place had to exist inside Heaven and Earth's domain, which required something more than formations or inscriptions to remain hidden.
The different space-time array and Cursed Reality's power could probably do the trick, but Heaven and Earth would eventually notice the Labyrinth anyway. After all, as long as something existed, the rulers could find it, especially if it remained in their domain.
Still, countless years had passed, but the Cursed Labyrinth had remained hidden. It didn't matter how many powerful experts had ended up on its floors. It didn't matter how much energy Cursed Reality stole from the higher plane. Heaven and Earth didn't find the imposing and spectacular structure.
There had to be an incredible power at work to keep everything hidden. Cursed Reality's world seemed to deal with the space-time array, so Noah viewed him only as a partial culprit.