|
They're allowed to take any human language from anywhere in the world, yes. Obviously as far as flavor goes, you would want some sort of explanation for how they were exposed to that language--it's obvious if you say, have a kitsune whose family crossed the Crown of the World (as Tien merchants do time to time) pick up the languages of Avistan. And keep in mind anyone who lives in or near Goka is exposed to a near endless amount of cultures and languages, and most of the people of Amanandar also speak Taldane.
As for the kitsune having Sylvan and Gnome on their bonus list, I have the DE primer but not the Gazeteer and so may have missed something somewhere along the line, but while speakers of those languages don't seem to be too common in Tian Xia, it could reasonably be said that kitsune would deal with them more often than many other races, having alot of similarities in outlook (not to mention innate magical powers). I don't see anywhere that lists gnomes as having a high population aside from Goka, but that doesn't mean they don't have any sort of population scattered through the Dragon Empires. Fey are listed as being major at least in the Forest of Spirits alongside the kitsune, so that's even easier to see.