and most importantly all those exsposed screws will hold your house together in one of those noreaster storms ( think thats how ya spell it)
as far as what your have under your paint, i dont know.
not a big fan of painted metal.
it could be crushed up yoo hoo cans, under there, for all you know.
if you dont allready have them, then when the time come to change out screw(s), you mite want to use a stainless screw with seprerate stainless, rubber bonded, washer. and use a good nickel size washer if ya can.
if the screws you have now are stainless , then you probably got a good roofer to do roof (average roofers will use whatever comes with metal).
so good luck, keep roof and gutters free of debri, wash it every once in a while just like a car, and you should be allrite.