Are stems files legal?

I know this sounds stupid, but I’m from Italy and the regulations surrounding the djing world are really obscure.

To give you some context you have to pay a fee to copy the file you own on a usb stick(YES! EVEN IF YOU PAID THEM) and it’s like 240€ per year (it depends on how many tracks you copy).

I create my own stems with python (stemgen by Axel De La Fosse), but I was wondering if the GUARDIA DI FINANZA can accuse me of having illegal copies and fine me 103€ for each file.