I don't think Estinien ever worries about the WoL, not because he doesn't care, but because anything you do he just assumes you'll succeed, even if it shouldn't be possible. You brought Ishgard and dragons together, you and Alphinaud saved him from Nidhogg's eyes, and then you immediately freed two more countries, of course you're going to save this other world and bring the scions' souls home. He doesn't really understand it, but it sounds like you have it covered. The world is ending? Man it's a good thing we got you on our side. Fought a god of despair at the edge of the world? That's a Tuesday for you, right? The WoL is seemingly dying on the spaceship floor? Nah, watch this, they're gonna perk up in about ten minutes and give us each a high five. (Alisaie smacks him for saying this, but he's absolutely still right.)
Estinien may not be the smartest of the scions, but he is wise, and he may not fully understand what plot armor is, but he's definitely clocked that you got it.
