It may possibly be a timing issue as far spraying for brown rot or a frequency issue. Could you provide a detailed schedule with the timing of the sprays and what was sprayed on each date? Heavy rains also can require spraying weekly at times.
The chemicals seem fine in general… there are some things that could be changed that might help but I don’t think that is the main problem. You might take a look at this thread that discusses brown rot on peaches especially posts by Olpea (he grows peaches for a living in the Midwest). I think the thread’s information can be applied to pretty much all of the stone fruits as far as brown rot. Also there is a list of peaches resistant to brown rot in my post.
Apples and pears could be bagged with ziplocs which would help with insects that show up later in the season. Stone fruits could also could be bagged but you need bags that breathe to keep the fruit from rotting such as the Clemson bags that Ahmad suggested.