Hello,
This is not related to the Turkish language. The letter q is a standard letter, and when written as Q, it is simply its uppercase form. As you may recall, there was previously an issue in MBraille where some Turkish characters could not be entered in uppercase, and you fixed that problem. The same issue now appears to affect the letter q. It can be entered in lowercase as q, but it cannot be entered in uppercase as Q in MBraille.
I hope I have explained the issue clearly. Thank you very much.