For the curse cards, I did consider some of these complications. I have a mini "law of root" document attached that goes over the complications with curse cards.
My ruling was that curse cards cannot be placed into special zones like the Decree / the Retinue, since curse cards don't have a suit so they couldn't be used to do anything. (And in the Eyrie case they would immediately turmoil). I didn't consider the case with the Eyrie where they MUST place a card and have only curses in hand. I think in this case it would make sense that they would have to use the discard mechanism to replace a curse with a real card, so that they would have something to put in the decree.