My short answer is: Ghostwriters aren't a big deal in Zimbabwe's Zimdancehall music.
Long answer is: I am saying this because from what I have picked up it appears to me as if you are asking 'are ghostwriters bad' and in the case of Zimbabwe's Zimdancehall music, I don't think there is any stigma or loss of integrity attached to artists who may use services of ghostwriters.
My answer is also supported from the basis that there is a huge cultural difference between Zim Hip Hop music and Zimdancehall music.
Hence, your question of ghostwriters being ethical is more suitable in the case of Zim Hip Hop since it is the genre of music in Zimbabwe which most the time follows standards of American Rap music although there are...