I was able to use those letters in CSIDE, and they seemed to run fine, even when I compiled the game.
They’re not included in the available characters for the User Dictionary yet, so you couldn’t start compiling Turkish words that way if you wanted to (and CSIDE only comes with English dictionaries built-in), but it’s possible those characters will be included in the next update to CSIDE—although @CJW, who created CSIDE, can confirm or correct me here.
I hope that’s helpful!