"Are you Dewi Lingo?"
Translation:Dewi Lingo dych chi?
We use this type of sentence, an emphatic one, for things like names and jobs. The emphasis is placed on the first word in the sentence. Your suggestion is not grammatically incorrect but people don't normally say that.
Apologies if you were marked wrong for your suggestion, we have included that pattern in similar sentences but the sentence above was deleted by us a while ago and we're waiting for Duolingo to remove it from the course.