You can say "잘 했어요" By the way, I would like to let you know about some rule of korean. You said “Good job”를 한국말로 어떻게 말해요?" But You would have to say “Good job”을 한국말로 어떻게 말해요?" like this. It must to say form of "를" , when after bowel sounds.

*VOWEL It was a mistake hehe.