I have to agree with the guy who owns this website when he said:

"And here’s a pet peeve: I don’t use apostrophes in the middle of words. It drives me nuts, and yet it’s all over fantasy literature and gems as the poor man’s method to make something sound exotic. Well, forget it, no apostrophes."

If it's pronounced to be pronounced TUHN-luch then give it a spelling like this Tunluch or Tuhnluch or even Tuhn'Luch. If you want vowels to be pronounced in there, then put some vowels in the word.

But now for other things.

How does the redudant exo-skeleton work? Is it mostly for roleplaying purposes or does it serve a game function.

You describe the exoskeleton of the Clr'chni as being soft but you give them a +1 Armor class Bonus. Does this mean that it is soft compared to the other classes, with harder shells? If it really is soft, should it give an Armor Class Bonus.

I really like the Consumate Profesional trait. It fits very well with this Racial/Caste system.