How to type `control + [` on a German iPad Smart Keyboard
I had an issue where I couldn't get a question mark to appear using the Apple iPad Smart Keyboard with the German as the language, I would switch back to English for punctuation. I just found that you can have the language set as German but then change the keyboard hardware settings to English and now my question mark button give me a question mark. Yay! 
So it may work for your situation too. On your iPad go to Setting > General > Keyboard > Keyboard hardware.