You need to define the default language in transposh, the wordpress install language does not matter, on the option page – drag German to the top to replace English as the default, and hopefully it will work
Unahitaji kufafanua lugha default katika Transposh, WordPress kufunga lugha haijalishi, kwenye ukurasa chaguo – Drag Ujerumani juu ya kuchukua nafasi ya Kiingereza kama default, and hopefully it will work