I love the The Witcher franchise also I love the fact game has Turkish language support. But Xbox version of Witcher 3 DLC's have problem with that. Turkis Language works fine in main game but in the DLC's Turkish subtitles is broken. Please fix for best gaming experience
HoS and B&W quest names are missing in Turkish Language. Base game doesn't have this bug. People say GoTY version doesn't have this bug too. But I bought game and DLC's separately and get this error in every extension quests and dialoges.
I had this happen on PC, but only once. In that situation, it was that an update did not finish the installation process. Some leftover files were active in directories, and some configuration files still pointed to the wrong directories.
Try manually running the installation / repair for the base game, the 16 free DLC, then HoS, then B&W (in that order). If you have the GOTY edition, you should only need to run the installation repair for the game itself (all of the DLC content is included). Not sure if that's possible on XBox, but deleting the content and reinstalling is worth a shot, if nothing else.
If that does not rectify the problem, it is probably, unfortunately, something in your save-state. As long as the quests work, it's nothing too big to worry about. Annoying as it may be, beginning a brand new game may be the only other option.
EDIT: Ah...I see you're also using the Turkish language pack. Seems it could be an honest goof with that pack.