It is correct, Halle (Saale) is the official name. Do you know anybody that when referring to this city calls it "Halle, open parenthesis Saale close parenthesis", since that symbol can't be pronounced even if one wanted? If you still think it should be written like this maybe you should remember the wiki guidelines for the name key, which say that the name should be the most common name (which is not always the official name).