Hi,
I don't think my problem is something about a missing file. I have succesfully run the very same program on UNO. Therefore I was thinking about a missing / wrong definition for resource inside the mysensors library for ATmega32u4 mcu.
To ensure that my micro is working properly, I have uploaded the sketch under Examples->1.Basics->Blink. It works without problem, I can see the serial traces as well.
Nevertheless I would like to try what you have suggested, but it is not clear for me since I have recently joined to Arduino World
Regards