I feel like hidden rooms aren't very transparently shown in the game. Currently there are usually 2-3 hidden rooms in each area, with an additional hidden room for every floor that has "many secrets". This is all totally fine, except that its sort of hard to identify them, even as someone that's rather familiar with what they are. By identify, I don't mean to search for them, but to actually identify whether a room is a hidden room or not.
My suggestion would be that all hidden rooms share some kind of identifier. some suggestions would be:
uniquely colored door that, even if burned, has a different color so you'll always know that was an entrance to a hidden room
Uniquely colored flooring
Uniquely colored walls
Indications in the logs when you step into an area or floor ("you have found 1 of 2 or 3 hidden rooms in this area" "There is one discovered hidden room on this floor")
Hidden rooms can affect your rankings score so allows for easier ways to track that would be welcomed.
The first 2 points can apply to regular rooms, I'm pretty certain.
They look very different if you're very very familiar with map generation of the game. It's not very obvious otherwise.