Denaturalization/ Do you need an official interpreter even if family members speak Turkish?

Good day,

I have dual citizenship, German and Turkish, but was born in Germany. I wanted to denaturalize in Turkey because I only want to be German because that is my homeland. At the time, I extended my military service; the next step I wanted to take was to denaturalize, but the people at the Düsseldorf consulate said I needed an official interpreter and that no one from my family or circle of friends could translate for me, which I find ridiculous because I had my Turkish colleague with me throughout the whole process, and he always translated everything for me. Do you officially need an interpreter?