Honestly, it should be an obligation. DB should make it one for themselves. DB carries millions of people a year that do not speak the language. Important information like route changes should be available to them. English just happens to be the most likely language to be understood at least enough to ask staff/other passengers as to what is going on.

I'm a native English speaker. It is not their obligation to provide everything in English. It is arrogant for someone like me to presume it should be.

If preventing people that struggle with the local language from getting confused or missing stuff is the goal then they're likely better off doing it in Turkish or Arab.