The red ball and the blue ball exist as physical objects, it is us, the observers, who are unaware of whether they are red or blue at either position. There's no superposition here. They are red, or blue, assigned randomly. Not both, not none. These are facts - properties - about the balls that are real, that exist, but we simply don't have that information at that point. It is meaningless that there is no observer that can 'see through' our hands to know which is correct.