Why do either of those start with X? Stuff like that ticks me off!X of course needs to be Xorn, not Xill.
Words that start with Y and then another immediate consonant are usually pronounced as if there's an I in there. So 'ythrak' would be 'yithrak.'You know, I can actually see using that, although I'm not sure anyone knows how to pronounce "ythrak," or would try to do so in a battlefield situation. Likewise, "troll" is probably more common (and more clearly pronouncable) than "terrasque." I'd probably flip "neogi" for "nixie" as well.
It's fun to stay at the ...