Okay, this goes beyond not speaking English and is starting to look like not understanding the general concept of communication. It's not that Evelyn has never encountered kids this unable to, well, engage, but usually the reason they didn't understand the concept of communication is that they were one. This girl is not one, and also not severely developmentally delayed, probably, given that she's a) standing up and able to repeat sounds and gestures, and b) probably managed to cause an enormous disaster. (Evelyn is going to continue not focusing on the enormous disaster part, that's the kind of thing you address AFTER you've built some trust and are sure the child is calm.)
Maybe she's very autistic? Maybe she's one of those feral children raised by wolves and has never encountered a fellow human being before?
...Evelyn is Making Assumptions and has to stop and remind herself that she has no idea, actually. She can try to get more background LATER, from one of the grownups who presumably did not just wake up mysteriously in this medieval city and can thus fill her in on the leadup to them, uh, apparently summoning her. To be a hero. To solve their problems. Which so far do appear to include a confused, sad young girl, which is at least vaguely in Evelyn's skillset.
Evelyn is feeling pretty unsure of how to best handle this, but she ALSO knows that looking unsure of yourself in front of children is a great way to get them to act up MORE rather than less. She needs the girl to see her TAKING CHARGE here.
She walks confidently over - though still not very fast, and still trying to move in a non-threatening way - and holds out her hand. "Do you want to come with me, and we can find somewhere more comfortable to sit? I bet you could use a drink of water."