Going to have to re-read the previous stories before a full reply, if any, can be made. Still, obvious unresolved questions exist, such as:
Were The Ancients just out taking the air, does their appearance bear some relation to Nall being an ass (see, it's not just Meelo), or is Something Else going on?
Whatever happened with Emily Wong, intrepid girl reporter? Did she ever get her promised payoff?
Who's watching the old homestead(s) back in The Big Universe(s)? There's a strong appearance of the Trinity having pretty much given up on living or travelling Outside, and count on people coming to see them instead (hence all the techno-magic communication systems across the Void).
IIRC the baby World Engine automates most, but not all, of the Pillar's duties to Cephiro, so what's going on with the things the Engine doesn't take care of when the Pillar's spending massive amounts of time not just not in the same universe, but in a parallel dimension as well? Is this helping dear old Akio run around unchecked (and will Akio be checking out the old homestead(s) in The Big Universe(s)?)
Akio aside, does anything happen in the Diqiu universe when the Avatar goes off to a non-Diqiu-ish Spirit World, such as Valhalla?