There is an ECO setting on the air conditioning in the Seal, if that's set then cooling is hopeless. I find my Seal's cooling to be excellent.
The roof panel is silver coated on the outside in the factory. It will get hot if parked in the sun and if there is an aftermarket tint on the underside then it will get even hotter.
I have not found there to be much heated transmitted in from the glass panel, but if you park in the sun then the glass panel can get very hot, the airflow over it as the car is moving, keeps it cool.