I've had this same recipe for years, I use it all the time. The only changes I make is to use 1/2 of the amount of sugars. It's easy to adjust, after you coat the apples just taste them, and adjust the amount of sugar accordingly.
This was ok- not great. I reduced the sugars and the filling was still sweet but runny. I would recommend boiling the apples first with sugar and about 2 Tbsp. of water in a pot so the filling is basically done and thick and then bake it.