Can The Hand's Judgement be used to cancel an Event when it comes out of Shadows? The Shadow rules seem to imply that it can ("After an event card comes out of Shadows, it is treated in the same manner as a non-Shadows event card played from a player’s hand."), but I would like to be sure.

According to the Shadows rules, once an event card is out of Shadows, you treat it (and Respond to it) as if it had been played from hand. So yes, anything that can cancel an event played from hand can cancel an event that comes out of Shadows.