İ think your answer should be accepted Also, as in Arabic جارته روزا could be translated to "his neighbor is rosa" or "his neighbor rosa is ....nice/tall...etc"
To make it easier you may use the verb كان/تكون which is something similar to verb to be, So you may say His neighbor is judy --> جارته تكون جودي
His neighbor judy is nice --> جارته جودي تكون لطيفة
Although that's not how we speak normally
:) The sentence above is clearly out of context, or what we call "Incomplete sentence". the reason for ambiguity is the name "Rosa", which cannot be indefinite, so one cannot tell if "His neighbor (the) Rosa" or "His neighbor Rosa"... To simplify, if the sentence was "His neighbor is a woman", versus "His neighbor, the woman, is..." the second is obviously incomplete. But we know that in Arabic by the definite article (there is no "is") :
جارته امرأة: His neighbor is a woman
جارته المرأة... His neighbor, the woman, is...
The جارته روزا sentence can also mean: جارته هي روزا = his neighbor is Rosa. You may see it in Quran, ذلك الكتاب (this book) means ذلك هو الكتاب (this is the book).
However, I think the marking of Duolingo moderators is strict for this. They don't accept another meaning. It's a bit weird for a hybrid language which mix up between MSA and dialect.