How Difficult is it to travel from Hieldelburg to Saltsburg by Train?
Not difficult at all. You can find schedules on the German Rail (Bahn) website. However, you will probably have more luck if you put in Heidelberg to Salzburg. There is a direct EC (Eurocity) train leaving Heidelberg at 9:14, getting to Salzburg at 14:09. It goes through Stuttgart and Munich, but you don't have to change trains there.