In truth, the cosmologies are not actually split by writer. They are split by continuities that happen to align relatively consistently with a single writer, but that isn't without exception. We allow a lot of cross-over when there's a clear reason to do so. We aren't talking about splitting up Superman into a key for everyone who wrote him.
DeMatteis, for instance, played in his own isolated cosmological sandbox that incorporated very little of what other writers were doing, and no other writers really pulled anything from his work. Pralaya, for instance, is best understood as existing in a DeMatteis "vacuum" of sorts because no one else has ever referenced her existence. Envisioning a composite cosmology where Perpetua and Pralaya have some sort of scaling chain between them, IMO, is really just not ideal at all.