Semi-gloss or satin is correct, flat and gloss are not. Everything on the grill including the rivets are painted. I would try to find at least three different semi-gloss shades, one for the engine compartment, one for the grill and one for brackets, engine, hood latch, battery tray. The latter should be the shiniest. There's no reason, the differences are a nice detail. Keep in mind that most brackets were dipped.
Jim
PS: The back side of the corral is almost a flat black.