"Dw i wedi yfed coffi."
Translation:I have drunk a coffee.
Many non standard dialects use the past tense for as the past participle. This has been a distinction between standard English and non standard English since at least Dickens day. Standard English is drink drank drunk, even for North Americans. I do hear a lot of people, even news people, using forms like I have went and he has swam and we have drank. I shudder when I hear it, but make note of a probable eventual change in usage. I'm not sure if this change will ever be completed or accepted, but in the meantime, since the English in Duo is at least moderately consistent from one course to another, it shouldn't be accepted here. Lot's of people ladder and are learning a third language through their second.