Translation:That girl is cute, isn't she?
That would be あの女の子、かわいいではありませんか。The ね particle softens the statement, which is often interpreted in English as "... isn't X?", but it doesn't make the sentence an actual question. It's more of a rhetorical question.
I think their confusion comes from duo adding "isn't x?" to every previous "ね" statement
So, separating them with a coma is the same as saying:
That girl... she is cute, isn't it? = literal translation (because there is a comma after the あの女の子 If the answer is That girl is cute, isnt it? then the Japanese should be without the comma, but a は