Couldn’t both cities have had gardens?
So far, of the two, only ancient Nineveh is known from inscriptions to have had gardens. I included the quote from another academic — that nothing has been found at Babylon, but that doesn’t mean it wasn’t there — to show how weak that is. If the translation was indeed wrong, the Hanging Gardens of Babylon lose their sole evidence of existence, iow, they’ll prove to have been a modern invention.
My thoughts as well.