To be clear I'm not a physicist, but I'll try not to get out of my depth: I would say that the unobserved hand is and always has been (post entanglement) in th

To be clear I'm not a physicist, but I'll try not to get out of my depth: I would say that the unobserved hand is and always has been (post entanglement) in the handedness dictated by viewing the other and the superposition merely refers to the indeterminably of that state -- which is still indeterminable from the POV of the persons with the unobserved hand[0] despite the first hand being observed. The superposition of both particles however has collapsed from the POV of the observers. [0] Until they get a phonecall at less then or equal to the speed of light from the observers of the observed hand. You can also imagine this is a pair of entangled Schrodinger's cats - one alive and one dead. On observing the live one there isn't a force or mechanism[1] by which the other one is instantly killed; it was always dead. [1]If there is, then it transcends space and time such that the cat dies in the past and so appears to have always been dead in the present.