While Hermione has spent almost half of her life in the magical world, it was still just a community within the same world as Muggles. Actually traveling through different worlds or realities or what-have-you? It's not exactly something she's overly familiar with.

Hermione has likely been lucky in most of her encounters with people here in Thedas. Or perhaps it simply has to do with her being young and honest, and so likely not widely believed to be a threat. She can prove that idea wrong easily enough, but at the moment, it doesn't seem wise to antagonize anyone, so she doesn't.

"So you mustn't be from one of the old wizarding families, in that case," she decides when Emma claims not to know about elves. "But at the same time-... er, don't take this the wrong way, but you look a little old to be a Muggle-born who's recently discovered her magic. I only say that because my school accepts witches and wizards when they're about eleven years old, give or take, and even the Muggle-borns start showing signs of magic before that. Is that not the case, where you're from?" Whether that's America, Canada, or a distant land Hermione's never heard of.