Venat's reason for going for the Sundering is multifaceted, and I think it's both very important to recognize that and very personal which part you considered most important. Like, I think that the reasons the writers and evelopers, when they did a lore Q&A, focused on 'she had to stop Meteion' part in their answers was because they're the writers and developers, the most important thing to them is the structural narrative element, the thing that keeps the plot moving. That doesn't mean the other reasons don't exist, and in fact that reason was quite downplayed in the actual script. In the Anamnesis meeting they're rather directly focused on stopping the sacrifices; in the post-Elpis flashback we see Venat dovetail from that into talking about how humanity can't just hide from its problems and has to overcome things through hardships. And another piece of evidence is the Twelve's epigraph; while admittedly a step removed from Venat/Hydaelyn, it shows that her and her crew genuinely wanted to see mankind and their world succeed and wanted to help them along in their own subtle ways; only the Unnamed Thirteenth had a focus that didn't mention mankind at all.
I'm not especially interested in arguing with Rosenstrauch, because we're coming from greatly different approaches to the game's story that care about different things. They write fanfiction; they're focused on the what ifs, the might have beens and things that could have been happening off in the background, because that's where they weave their own stories and find their own fulfillment. But personally, I'm interested in the lore as it relates to the story we've got and the world we're given; I'm interested in the concrete facts, the direct evidence and how it relates to the rest of the story as it is, because that's where I find my fulfillment.
Neither of those is necessarily wrong, but they do lead to a fundamental difference in how we approach what the game tells us. I hear 'we can't tell Hermes or he'll start working against us' and go 'yeah that makes sense, we saw him say and do literally that before he got memory wiped'. Rosenstrauch hears it and goes 'but what if instead that didn't happen, what would happen then?'