"Avatar" timeline could still qualify as a designation in universe - if we're taking the events in the Avatar duology as our "point of divergence," then the divergence happens at the discovery of the Ohalu text in B'Hala, chief among them the prophecy of the Avatar. That said, I can roll with George.
Somehow, me and my friends in the real world have started calling the Litverse "Typhon Pact Continuity" so that's what I'm sticking with. At least until I learn what the name given to it in Oblivion's Gate is.
I doubt that's really the in-universe point of divergence, though. It's the start of the systematic effort to construct a unified novel continuity, but that continuity ended up folding in a fair amount of earlier stuff and adding stuff set earlier in the timeline.
So by convention the novelverse should be the Pluto Timeline! I'm personally partial to "Destinyverse", but it doesn't really work well in-universe. One of the defining characteristics of the timeline would seem to be the Borg Invasion, but not sure how to make a good-sounding name from that. Since the invasion directly led to the formation of the Typhon Pact, maybe "Typhon Timeline" would be appropriate? I think an argument could also be made for "Tezwa Timeline" (or maybe "Kinchawn Timeline"?). Although it sounds like our speculation becomes moot in about a month anyway!
I like Typhon or Typhon Pact timeline, since the existence of the Typhon Pact is one of the biggest differences from the other timelines we've seen. Borg Invasion Timeline is OK too, but Typhon Pact is quicker and easier to say/read.
What comes first into my mind, somehow, don't ask, when I think about the Novelverse is how two Federation Presidents were assassinated. I propose, then, it be dubbed the JFK-verse. Other than that? Janedeath, maybe?
Lots of different interesting ways to pitch it, that would be in-universe consistent. The Caeliar Timeline, or the Caeliarverse, for one - as their species and link to the borg was quite profound.
Also, though maybe the Coda treatment tying up the litverse is a chance to shuffle the depressing latter New Frontier books into that alternate timeline, getting rid of the rest of New Frontier would be a waste. Most take place long before the Borg invasion and such that make the litverse hard to reconcile with Picard et al.
Well, we have, as Coda is set in 2387, though it wasn't established when in the year the supernova occurred. But we now know from Picard that there were years of advance warning for the supernova, which hasn't been the case in the novelverse up to early 2387. Which is why it seems unlikely that the supernova would happen in that timeline.
To me, it feels that Coda negating a supernova for this timeline because of and in spite of canon works winds up lending more credence to the frame story of ENT - The Good That Men Do (which was of course written before the Abrams / Kurtzman era).
I propose we call it the Kelvin-Timeline Timeline, because apparently the Kevlin Timeline doesn't exist within this timeline.
Honestly, I always thought of them as the "Relaunch" books. So "Relaunch Universe" seems simple and straightforward.