"Dw i wedi cael gradd dda yn y gwaith cartref."

Translation: I got a good grade on the homework.

[pioden-wen]

No-one would say 'gotten', surely. It's an Americanism. We should be encouraging learners to be accurate in both English and Welsh.

[EllisVaughan]

"Have gotten" is a perfectly fine way of saying "got", American English is just as correct as British English.

[pioden-wen]

More correct in Duolingo's view, apparently, as the British English alternatives are assessed as 'wrong' and the sentence keeps recurring until the learner is forced to type 'gotten'.

[EllisVaughan]

Then report it if it's not accepted.