The app interface is available in five languages: Türkçe, English, Deutsch, Español and Français. Change it with Language in your account menu at the bottom of the left menu (click your name); your choice is saved to your account.
In German, Spanish and French, some newer screens may still show in English. Insights findings are prepared in Turkish and English.
Emails are independent of the interface language: with the Generation language picker on Generate Emails you can have them written in any of 46 languages. So you can use the interface in Turkish and still prepare German emails for buyers in Germany or Arabic ones for the Gulf.
Support is given in Turkish and English.