Iomedae is trying to think like a god.
She's already tried thinking like a mortal about everything she's seen since she came here - the conversation with Starwind, the destruction of the village, the miserable day in the forest, the conversation with Vanyel and his song-sorcerer to whom he is magically bonded. There's a lot to think about, but surprisingly little to productively think about. Either Vanyel is being basically truthful, or he isn't; most likely someone ordered the village destroyed in response to her, and either it was Leareth or it wasn't; either Leareth is as he presents himself, a humanitarian sort of Evil archmage, and will back down when presented with an alternative, or he isn't and won't.
(Would Alfirin, were she a thousand years into a plot to create ascension at unfathomable cost in a world that had only ancient alien gods, back down because Iomedae arrived from another world claiming there was another way? ....depends, a great deal, on what method she chose to endure a thousand years so she could do it. And on how much she was giving up by backing down. And on whether the cost still felt unfathomable, after that much time fathoming it.)
So thinking like a mortal grinds into 'this is very confusing', and Iomedae has decided to abandon it in favor of thinking like a god. To think of a god is to fragment questions down into floating tiny subquestions, and then assemble them back up from there. It's very meditative. She's fragmented the whole conversation with Vanyel, all the bits that could have been lies, asking for each of them what features they'd give the world around them, what further lies would be needed to maintain them -
- doing this makes it very clear that Vanyel is a very unusual person, as you might expect from a -
- from a paladin of a god that prohibits challenging the gods. Because that's what this is, isn't it, taken at face value. A god that is maybe Good in some ways, but a god who you cannot survive renouncing and who isn't good enough and who will nearly renounce you for wondering if Leareth has a point.
It is a kind of slavery, however gentle and however often genuinely Good. It is - something that can only ever nourish human potential up to the point where humans start writing screeds against the divine, as they do, as is their fundamental birthright and entitlement. Something that has to prune them, the way the fear of damnation prunes people but even worse, because at least you don't face damnation for saying that wresting creation from Pharasma would be worth paying almost anything short of what it would almost certainly in reality cost.
From a human perspective it felt like there were lots of possible explanations but when she thinks about it in fragments reassembled it - doesn't, actually. It feels like the area where the truth sits is already pinned down.
It turns out that when she looks at the world like a god she's surprisingly sympathetic to the guy who wants to murder millions of people.