Was it hard learning Kurosian? Is Kurosian all they spoke in Kurosia?

Lost Queen : Yeah at first it was difficult, but living among the Kuros really helped. 

We did speak a few languages, depending on the dragon mostly. I can speak English and Kurosian fluently, but I can only read Arkeyan. I have a hard time speaking it, but it was a requirement of all Kuros to at least be able to read it and understand it.