"What are human."

"Not Elves," says Kiri.

"I know you're not an Elf. You're not tall and you don't have the hair or the ears and you aren't hurting me."

Kiri opens her mouth, makes a helpless gesture, she doesn't speak the language not really. "Not hurting you," she echoes.

"There are Elves nearby and they will kill me, will you help?"

...Wobbly gesture.

"Will they hurt you if you help?"

...Wobbly gesture. "Maybe." For certain categories of help. Need more words, need you to ask better questions...

"If you let me go, the Elves will hurt you?"

"Maybe." If she does it too soon.

"You aren't strong enough to fight them?"

"I am..." Wobble again.

"Then you don't have to let them hurt you!"

"I don't have to let you hurt them," Kiri says.

"They're Elves, I hate Elves and kill them."

Nod. "I don't have to let you."

"Elves are bad."

"You -" Ugh, unidirectional communication with a person whose thoughts are deliberately constrained is hard. "You hate them," she emphasizes.

"I hate them because they're Elves."

"I don't hate them."

"But they'll hurt you if you help us, doesn't that make you hate them?"

"I -" Frustrated gesture. ...She reverts to Welchin in the hopes that suddenly being incomprehensible will get across the sentiment if not the details of "I can't actually speak your language and it makes it very hard to be precise about anything complicated I want to communicate that you haven't happened to think of".

It doesn't understand her? But it seemed to understand her. How to make it understand...

"I understand, I don't -" She taps her mouth.

That does not make much sense. 

"Okay. I can teach you? Or tell you things? But the Elves might come back and kill us. At least me."