I get that this is the first time we’ve had more than 7 crystal beasts in the game so the ruling seems weird. but i am very confident that there is no reason why 8 should make it unsummonable. Cant find anything online about this but until there is a konami sourced ruling, this is a bug. Ive spoken to 2 judges now who have both confirmed 8 shouldn’t matter. I’ve been allowed to do this IRL since the text does not state that it has to be exact