The specific price rule is applied when the date specified in the rule is the current date not the booking dates. If you want to provide discount for the booking dates, you have to use feature price plan.
Right now the default functionality is exactly the way you described. That means you will have to add a room at a time in a room type then enter its room number and floor.
But what you are asking is also achievable through customization. Which will be a Paid Service.
So if you want to for it then please raise a ticket so that we can have a one on one discussion. https://webkul.uvdesk.com/en/customer/create-ticket/