How to tell whether ケンカ is fist fighting or quarrel?
I mean it's unlikely the twins would punch each other hard.

lookingfrank said:

How to tell whether ケンカ is fist fighting or quarrel?
I mean it's unlikely the twins would punch each other hard.

By guessing the situation? She doesn't look like to have any injury so it's can't be a fist fighting.

firechikara said:

By guessing the situation? She doesn't look like to have any injury so it's can't be a fist fighting.

So the commentary translation seems to be "ambiguous".

lookingfrank said:

So the commentary translation seems to be "ambiguous".

You don't have to necessarily punch someone to have a fight, a fight can also just be words.

Yup, just like what Sythini said. I understood it this way too.