It could be argued that Doman-common, or the "common Doman tongue," is, in fact, Japanese. That the Xaelan tongue is different. We do see Japanese naming systems in both spells, items, and even their actual names. So it's less, "They can't speak this language," and more, "They're speaking Doman, not Raen." The actual lore quote is:
Some food for thought! ./bouncesout
Some food for thought! ./bouncesout