I really, really, really like the idea behind Asteleben. His worshipers could make for some mighty interesting villains, or heroes even.
Icedaemon mentioned that culture would be determined more by non-material things, like religion and language instead of a particular homeland; I think as an outgrowth of that there should at least be one Mystery Cult
style secret religion (replete with secret hand signs, symbols, rituals and over-arching missions that affect international politics and may decide who ends up controlling any number of kingdoms and empires), that spans all of Cakeworld across racial and state lines.
As for the primordials, perhaps steal and slightly change one of the terms of Hinduism while mixing in a reference to the Grecian Titans? (Vistedenes comes to mind)
I think Death and Violence could be folded together to become Destruction, based on that being Shiva's domain in Hinduism. Likewise, Time seems more like a subset of Nature, especially when it comes to seasonal patterns, and the ever-moving flow of water towards the Rim- which might be deemed so important as to be defied itself, perhaps as a kind of impersonal fate-chance-fortune-luck deity? "May the Flow be with you", "The Flow directs all actions" that kind of stuff, similar to the Force.
To add more Grecian-type flavor, could the Creativity primordial come down in
different Muse forms, one for each specific artistic of technological form? And what of any children that may have resulted of God-mortal romances that happened during the battle, of in more recent times? Could their be blood-lines who dedicate themselves to keeping the blood of their God pure, perhaps with inbreeding as a result (A la the Egyptian dynasties and the Hapsburgs)?
In you description of the Mother primordial you mention the moon, but haven't included any physical description of what kind, and how many moons
Cakeworld has, or what effect their gravity would have on the tides.
Also, though this may be too soon, as the continual outward 'tide' has such a great effect on this world, I would think Darfellans would definitely show up. Perhaps they would be traders/mercenaries/travel guides who domesticate whale-like creatures that could hold land-dwelling passengers inside their mouths?
That's all I've got right now, but over-all this still seems like a freaking awesome idea. Great stuff so far, keep up the good work!