His knowledge? You mean like how he knew the humans weren't even real people? Or how he knew Corypheus would die unlocking the orb? Or how he knew you were killed by Alexius' spell? Or how he knew Mythal was completely dead? Solas thinks he knows what is what. He might be lying to make himself seem more powerful and in control to the Inquisitor. He might be lying to justify his plans. He might be mistaken because he slept for so long and forgot the true events. He might be mistaken because the Veil affected him negatively as it did the evanuris. He might be confused because the spirits in the Shattered Library were confused. He might be confused because Mythal made him forget what really happened. The last one is based on something Cole said in Trespasser when you talk to him at the palace and how she made him forget. It could be related to Solas, or it could be some obscure crossover reference.
The difference is that what you make in the Fade is a product of your will. Valor explains this in the magi origin. He created weapons from will. The worlds inside the crossroads, or even the real world (without the Veil interrupting the magic flowing to them) could have been the product of the evanuris' will. So cutting them off from it may have caused the structures to collapse. Would they vanish entirely? No, because they were partly in the real world. But it still caused them to collapse and degrade.
If she made it with her own will, then it wouldn't matter if she gifted it to June or not. It's whoever willed it into being.
I'm saying the spirit may not remember the details of it. The spirit might remember vague images of it, or may have recovered fragments of what happened, but is now presenting the best recollection possible, which is incorrect. In other words, it doesn't have the whole story. Think back to the Herald. What we saw play right after the character creation screen isn't what we saw play when we recovered the memories in the Fade.
In the other cases we asked things that were too specific, or about subjects the spirit could not recall even in the slightest.
Did Wisdom's domain remain? We have nothing but Solas' vague statement to go on. But as I recall, he only mentioned that Wisdom may appear in the same place, though in a different form. What is this place? Is it Wisdom's domain? Is it the Raw Fade? There are no specifics on the matter. And even if it is Wisdom's domain, is it the same as it was when Wisdom occupied it? Or has it changed form, thus no longer the same place?
Yeah, notice how you're grasping at straws to defame the one person who probably knows anything about this subject, all to justify a theory that requires several large assumptions on the nature of the Fade, assumptions which are pretty often contradicted? Like, at this point, I'm not sure what else to say. Surely you see how tautological this is? "Solas is delusional." / "Oh, why do you say that?" / "Because he keeps contradicting this theory I have." / "Well, how do you know he's not right?" / "Because he's delusional."
*Sigh* Why would he lying about this when there are far better lies he could've told? ("My plan is harmless and will kill no one," for starters) Why would he be mistaken or misremembering, when we've seen nothing to suggest he is? All the points he was wrong on before didn't relate to something he knew so intimately, and furthermore, they're assumptions that everyone else made as well (Seriously, if someone vaporizes a person in front of you, what would your first assumption be? "Clearly they've jumped a year into the future!" or "Gosh, must be dead.") If he's been addled by the Veil, or by sleep - prove it, then.
Onto "The Fade is constructed from will." Yeah, that's correct. But notice how the Valor spirit doesn't proceed to tell you that everything he's made will disappear if he's killed. Notice how no one else ever tells you this either. It's an assumption you've made, justified by other assumptions you've made, contradicted by a character who is, frankly, far more knowledgeable on the subject than you.
On the subject of June's place - that's the thing. She didn't will it into being. A bunch of slaves and some random architects did. So we have no reason to assume the Crossroads or the Vir Dirthara or any of it was based, specifically, on the Evanuris' will. And another thought occurs to me - the stones in the Crossroads and the Library. The ones you can activate into returning to their place. "They remember where they were supposed to be," Cole says. But who's remembering? Not the Inquisitor, not anyone with them. The stones themselves are. They're self-maintaining, and can reconstruct themselves. They're not dependent on their creator's will to continue. In fact, that they can remember and stray from their creator's will at all shows that they've some semblance of life of their own.
On Wisdom - Solas says the he returned to the place where she used to be. So no, no specifics. But given that there was a place to return to...
I mean, I highly doubt a millenia-old Wisdom spirits just hung out in the raw Fade all her life.