That should be correct. Korean, like many other languages, does not demand a continuous verb form to denote an ongoing action? There are many many sentences in Duolingo Korean that could/should be translated with an English continuous verb, but with a very few exceptions, Duolingo rejects the continuous English verb form unless the Korean has ~고 있다

That would be 누가 지금 싸우고 있어

Boxing? Opener done. Maybe now main event... Bad Papa will fight now.

I think it would be written like this 누가 지금 사우고 있어.