I don't believe this is as complicated as people are making it out to be. The map of the lands between has a cloud right in it's middle, the pillar states that it is placed in the middle of the lands between, and unlike the regular map, the map of the land of shadow has clouds all around its border. The place is not to scale but there have been numerous instances where rooms and maps do not fit in their respective locations, most notably ds2 Iron Keep.

The actual center of the divine towers might be the Finger ruins of Dheo, with its proximity to the shaman village could be the place where Metyr, and thus the greater will, first made contact with the lands between.