LooNEY_DAC, I don't think I've got anything to add to that; but I do think that's an interesting point. Thanks for bringing it up.
It occurs to me that when Lalli said he'd have to stay till he'd figured out how to get back where he belongs, Emil and I both assumed that he meant stay in the dream. What he apparently meant was that he'd have to stay in Emil's head -- including while Emil's awake.
Which is kind of an interesting twist on the dreamworlds; and implies that even for non-mages, the dreamworlds aren't dreamworlds because they exist only in dreams, but because they're accessible only in dreams -- but they must exist all the time. Or at least all the time during which the person who dreams in them is alive. Which would imply an underlying consistency to dreams which I don't think actually exists in the world that we're living in.
And since Reynir can move from one to another -- the entire dreamworld, everyone's together, may actually be one place, but most people can only get at their bit of it.
I wonder if it's made up of individuals' dreams, or is entirely independent of them and is just a place that Minna's characters visit when dreaming? but the fact that some of the dreams clearly reference individual memories (plus the incident with Onni's ear) indicates that it's related to waking world events.