As I said, I think it's similiar to the GoE. The middle, 0x0, but with the additions to MD and so on the actual middle isn't there anymore I think- thus creating a midpoint that has been shifted. I haven't precisely counted the rows and columns yet, but if Myths numbers are right, then that's even more reason to assume it is like that.
Per se you could define two midpoints: One point of origin, and one point of the middle of the results of changes (for whatever reasons).
As for the labyrinth and the actual reason why it has been shifted or is in this state, that's a whole another question. But I tend more towards shifted instead of saying it cannot exist unless we believe in it- because the fact that we can assume that it should be there but isn't there is similiar to the observers spot or even just a spot "lost in time". Claiming it cannot exist without belief would then be too imprecise.
edit: unprecise wording on cannot exist, changed to cannot exist without belief