Can anyone confirm the color of this promo's back? Would it be the wrong color as per adventurers?Yes; the wrong color is now the right color. Which is to say they have to all match, so they do.
If you shuffle Events separately then it doesn't matter much; ideally they would have an entirely new back but they don't. If you shuffle them into the randomizer deck then you will know when the top card is an Event, but again it doesn't matter much; you can always cut before dealing them out, and it's not like someone gets an advantage by craftily ensuring that there's an Event.