You really should make 'railroad boom'`s abilities possible to provinces with 30 or even 25 development, not 40. In my last game only few provinces reached 40 development even with Dynamized Development mod.

The young italy events are much like the Dutch revolts. Annoying and impossible to stop without either giving away development or micromanaging seperatists for 75 years. Much like the Dutch revolts, the decisions are binary, with no other interaction other than a massive peasant army which the suppress rebels AI will not attack due to size or giving away valuable land. I think it should be made a disaster that is nearly impossible NOT to trigger while providing a set of conditions which can be met to stop the endless revolts. When I have crushed 20 seperate revolts over the course of the first 5 years of the movement, I think they would get the point, thus when they keep coming, it ruins my immersion.