Quickly tested your suggestion, doesn’t seem to work. Since I have solved my bigger problem in a different way I´ll have a look at it later. However:
Casting a blueprint function library to UBlueprint is not a good idea (I know its from my initial code) because a blueprint function library is directly a subclass of UObject and not based on UBlueprint. However it also doesn’t crash probably because the used functions are implemented in a common super class anyway.
The FindFunctionByName does not find the function, its always null. I will have a debug session at some point and try to figure out how to do it.