“The turns in CO-OP are for who is facing the Retaliation from the Dungeon, so anyone can play Crawler cards in any order. The controlling player would have the final say in what is played.”
So can anyone also play Crawler cards in any order during ‘Step 3.2 ADVENTURERS ATTACK’? The coop rules do seem to suggest this would be OK (I ask as you specifically mention the Dungeon Retaliation).