I know what's wrong with your code.
When you check first if cam_lontana_sw is overlapping map_wall, you pick 1 instance of map_wall.
Then, when you are trying to check if cam_lontana_centro is overlapping map_wall, you are not testing all map_walls, but only that 1 picked instance.
If you modify the code like this it works:
Or you can wrap all checks in functions and use them like this:
And I have to agree with brunopalermo, the method you are using is not very efficient.