I must have missed the conversation where it is alluded to. Does it require Warden Alistair?
King Alistair doesn't have a conversation with her beyond "You abused our hospitality and are exiled from Ferelden".
Fiona has that conversation with the Inquisitor, where she cagely admits that she knew Maric a long time ago, in a tone that makes it clear she's obviously not telling the Inquisitor everything and is hiding something (ie. I hooked up with him and I'm Alistair's mother).
For Alistair if he's King, she asks if you had a chance to talk with him before he booted them from Redcliffe, while if he's a Warden, she asks about him when you meet him during Here Lies the Abyss... and if he died in the Fade, asks whether or not he died heroically?
No. Because these things make sense within the context in which they are presented within Inquisition.
For example: Varric says he met the new Arishok. Okay, good. But that could literally be any Qunari that did not have horns back in Par Vollen. It's never said that's Sten. It's only Sten if you've read the books.
Which brings up another point: if you left Sten caged back in Lothering, what did he do to regain his honor, his sword, etc. How did he make it out of the cage before the Darkspawn hoard destroyed the village? More importantly, why would he refer to Alistair as Basalit-an if he did not accompany the HoF during the events of Origins.
Another reason I refuse to acknowledge the supplemental material.
Which is why I said, it's pretty much down to constants and variables. If those characters are still alive, but certain things didn't happen, then they still probably happened as they did in the other media, but not necessarily in the same way?
Wynne can die in Origins, so presumably, the events of Asunder happened a tad differently. However, it's not hard to picture that the Divine asked someone to investigate reversing Tranquility, who ended up recruiting a powerful Spirit Medium, thus getting Rhys into the action, thus setting in motion the same events that happened in the book, just a tad differently? It's true that in this world, Evangeline would have probably died since Wynne wasn't around to sacrifice herself to save her, but it's just as plausible that perhaps Evangeline was luckier in this world and never got mortally wounded by Lambert, so she's still alive and well regardless?
Or to use your example of Sten? Perhaps he was freed before Lothering fell, went back to Lake Calenhad in the vain hope of tracking down his sword and managed to pick up the trail as he does with the Warden, leading him to Redcliffe to get it back from Dwyn? Then, he departed back to Par Vollen, having suffered far too much of Ferelden for his liking?
It's not hard to really see how things could have played out in some of these AU worlds to fit with the books. The only reason we don't have those things is because half of the decisions would require far too much time and effort being put into having to write every contingency for the games themselves?
Same reason as why if Kieran is alive, then he looks the same regardless of who his father was?