At the end of the book, Glim takes the not-quite-Hist trees (and by extension, Umbriel) back to their world. The folks in the kitchen all pretty much want to kill each other, and Glim sees some kind of tower on the horizon. Here's what I make of this.
* The tower? My gut says it's Adamantine Tower.
* The kitchen people killing each other? Might be nothing, might also be the Ehlnofey War mentioned in the Annotated Anuad.
* The not-quite-Hist trees? Ancestors of the actual Hist, meaning that Umbriel is, some day, going to be Black Marsh.
So, what I'm thinking, is that the whole thing's a wacky time travel adventure, and Glim is inadvertently responsible for the creation of the Argonian race, and quite possibly, the other races, too. Argonians already don't believe in linear time, so going from the Fourth Era to the Dawn, or perhaps an even earlier Kalpa, isn't that much of a stretch for them (and KINMUNE shows there's a precedent for this kind of thing, if the word "precedent" even makes sense when talking about nonlinear time).
I'm also wondering if there's a connection between the Ingenium and Lorkhan's Heart, which would play into the whole "the books are retelling the creation of the universe" thing, meaning that the key players of the books might actually fit into the roles of say, Anu/Padomay, or Magnus, Lorkhan, Akatosh and the rest.