Hello & welcome, gabriele !
When i have to Load the scrip file "badpixel. lua (into the folder CHDK/ScriptsTest), I can't see it. It seems it doesn't exist, but I verified it is there.
On a multi partition setup the first (small) partition is only used to start CHDK, only diskboot.bin and ps.fi2 (ps.fir on older cameras) is needed there.
When CHDK is loaded, the 2nd partition is used for all data, i.e. images, movies, CHDK files like scripts, fonts, language files etc.
--> so just copy all files from the CHDK package to the 2nd (big) partition !