Well, not random doesn't imply ID - it can just mean that the gate-progression is determined by some dimensional interplay based on the physics of each world. It can even be based on the golden section/angle which re-occurs everywhere in nature.
Of course, from our perspective as readers the Multiverse is definitely created by ID, aka rfc
.snip
I have a vague memory of this topic being raised at a Q&A at a con with Himself some time ago (Manticon 2018 I think) and the response was something along the lines that the in universe characters will eventually discover that the portals are the result of something akin to an "industrial accident".
Also mentioned was the there would be contact with a third civilization out in the multiverse, one with a technology level roughly equivalent to our pre WWII. And, like our world, these people have neither magic nor Talents. This civilization was somewhere down one of the other chains from the universe where the Arcanans and Sharonans met.
I personally suspect the implication is that this civilization is where said "industrial accident" originated.
I do hope we'll be seeing a Book 4 in this series relatively soon (before the end of the decade maybe?)
tj