What needs to be defined about crouch day? As you said, it's self-explanatory.
It says in the rules "Days/orders explained here do not have to be explained ingame. These are not the only days/orders available, but rather some of the more common ones."
Now, in some way, this seems like it's forcing the warden to explain Days/Orders not defined in the rules. If we go as far as to define crouch day, then we need to also define all the other days such as Jump Day and 360 Day and so on.
I wouldn't want to keep defining these days when becoming warden as they are self-explanatory, but there could also be an endless amount of days — for instance, LR days. Considering the logic and where you're coming from, these would also need to be defined, wouldn't they? Even though again, they are straightforward to understand, for example(s) Obby Day, Club Glod day, and it could go on forever. But in this case, you are forced to explain these days according to the rules "Games/Days must be explained fully every time they are played " This was under "Special Days / Rounds / Mini-Games " So the rules already got you covered on LR/Special Days.
It feels as though the rules are the principles, and you have to build the system using these principles and your discretion. Meaning, the rules don't directly force you to explain days such as Crouch day, Jump day, etc.. It moderately implies it. All in all, considering the number of maps that we have which only increases the amount of possible days & the fact that the rules do imply that you explain these days & according to this rule "Games/Days must be explained fully every time they are played " even if this rule is for LR/Special Days. I think we HAVE TO & SHOULD go by this rule not only for Special Days but for all Days and force warden to define.
While I don't necessarily like the idea of giving some smartasses on red what they want and defining everything even if they know what it means. Still, people such as new people and non-English people who things like this could genuinely confuse them, I think it's only fair.