I don’t know if this is useful to you at all but I know Chappell in particular has been known to be susceptible. I only have 2 pawpaw trees and my Chappell appears to be suffering from phyllosticta. I’m going to see how it handles things on its own, I won’t intervene unless the tree looks to be dying.
The link below also says Shenandoah is somewhat susceptible but in my own experience, it’s not showing any issues with that at all. I’m going to be selecting only the most resistant cultivars moving forward because I like things as spray free as I can get.