I saw tutorials where with super smash bros Rom you can update your emuNAND or its not possible?
I have seen posts about problems with exFAT. Have you tried FAT32?

I saw tutorials where with super smash bros Rom you can update your emuNAND or its not possible?

are you on the 9.0.0-20U emuNAND and 2.4b firmware though, GorTesK?