Any repair you make is going to be visible. You could try progressive attempts at buffing, but it's going to be labor intensive. You may be able to find a shop that can duplicate the piece. But, yes, some kind of super glue or that stuff you reference certainly can't hurt. To keep the crack from going further, drill a small hole at both ends of the crack. It's not guaranteed to stop it, but it has a very good chance of working. Then you can fill the hole with glue. Try to flex the crack open a bit when you put glue on it. Mask well.