Hawke understands unified, communal loss same way he understands religion, or philosophy, or any other undeniably relevant but alien abstract. The distance he feels might manifest as a symptom of how new he is to life in Zion, but doesn't: he'd feel the same way if he'd lived here for decades. He's not awkward or out of place because he has purpose here, but in temporary absence of said purpose does move mostly on the periphery.

He is, as observed above, far from the only one, but he's made enough acquaintances in the time he's been unplugged to exchange a nod here, the subdued version of greeting there. Their loss is not his loss, but it doesn't cost him anything to acknowledge it.

While Fenris's new ears might not be as sharp, maybe all that exposure to a Ferelden accent amidst a sea of Free Marchers was distinctive enough to have left an impression.