And to make clear why your solution did not work, if you use go.get_parent() on main:/instance1#enemy, you will not get main:/instance1 as a parent of enemy, as enemy is not a child object, but a component of the object. So the object you are addressing with main:/instance1#enemy is main:/instance1, and go.get_parent() will try to find a parent of instance1, which is nil if it does not have a parent.
So keep in mind the difference between objects and components.