So I've been thinking more. Sera's prejudices against the Dalish seem to be experiential, not philosophical; she doesn't seem to believe that the Dalish are inferior, so much as she's seen several be unpleasant to her and has thus expanded that to all Dalish. And it seems logical to me that having a Dalish friend/lover should soften this, yes? As it's a new experience that can counteract the previous bad one?
Could go either way, tbh. I mean if Quizzie took Sera to her clan and that was an okay experience, that might help? I mean, it is partially a philosophical one, because Sera percieves them as backwards thinking and isolationist, so if clan Lavellan ran contrary to that, she might see them differently. Honestly, I think it would take a lot of time and exposure, not just one person who seems to defy it.