“smart” keyboard for iPad doesn’t rotate through languages

Hi, I need to type in German as well as English. There’s a button on my Smart Keyboard that does rotate through the languages and let me choose the right one. Then any on-screen keyboard is correct, and the spelling corrections / auto fill is correct. But when I try to type from my keyboard it just keeps giving me English! Obviously this doesn’t happen with laptop keyboards. Is there a way around this, or is Apple just trying to take advantage of the fact the Smart Keyboards come off & force us to buy multiple? That wouldn’t be very sustainable…