In Unity, at least with the built-in shaders, all light values are multiplied by 2. So a light with intensity 0.5 is actually a light with intensity 1. I'm guessing this carries over to the lightmaps so that it's consistent.
Your set-up is very, very wrong. From the look of it, the point light is way above the room. Go to lightmapping, maps, clear maps. time to start again. Move the point light to inside the room and add a cube for a roof - IMPORTANT - make sure the cube is the colour you want the roof to be, usually the same as the walls.…
Probably some of the problems are caused because the large room has 2 smallish windows and a balcony facing away from the sun. First thing I'd do regardless is crank up the sky light intensity and the 'sun' light intensity. The sun should be a bit brighter; consider most programs vaguely calibrate light so that a…