Easy to say that the interaction length ^+307 cm is the problem
No: scintillation doesn’t limit the step, so it always proposes an interaction length of DBL_MAX. If you don’t see scintillation photons in your application, something is mis-configured.
When I try just to ./OpNovice2 and execute the different macro of scint_by_particle, i have an error at processActivation Cerenkov.
Without a macro on the command line, vis.mac gets run. This macro calls /run/initialize. But there are commands in scint_by_particle.mac that must go before /run/initialize. So, to run with visualization, move these commands to vis.mac, before /run/initialize.