So as I said, you need enough casualties for them to wake up, something that wouldn't happen if everyone teamed up against the Begnion senate.
Ashera would not have woken up without Sephiran's actions. Also I'm pretty sure Kurthnaga being royalty unlike Ena and Nasir had something to do with it
This is actually not true. Lilia was given to Ashnard by Lehran AFTER the Serenes Massacre. https://fireemblemwiki.org/wiki/Ashnard. Also I'd forgotten that Sephiran outright GAVE the medallion to Ashnard. So he was fully responsible for all of that, not just informing Ashnard. In any case, even after the war came and Ashera still didn't wake up because Goldoa didn't officially make a move and the war "didn't get big enough". It's only global war, the one that Sephiran facilitated that would wake Ashera, up. That's the whole point of his role in the story. His role is fine. His motivation, reasoning, and presentation is garbage, like Corrin's in Conquest's.
When Does Lehran give Lillia to Ashnard? I checked the source on the wikipedia, which links to serenesforest. I can't find any source saying that Lehran gave Lillia to Ashnard, and I don't remember it either unless its from the original Japenese or something.
---
Roy's our boy! One man's sunset is another man's dawn.