Update everyone :
I did did a backup of everyting on my computer before formarting the sd card,
I did the formarting, and i followed the tutorial that lone_wolf gave me and it worked ! I'm re-installing only what i use now (jksm and the thing...
It should work on a Japanese 3DS no problem. If you're using a homebrew userland only exploit though, you're not going to be able to open Street Pass IIRC. You're going to need an older version that I not longer have and full CFW for it to work...
Those images are VERY different things. PM is a error for the DS firm. and the other means something different from that. You cannot go by similar as they are all likely different.
I may try the new ram site, and download more RAM to my Switch. Not sure if ddr3 is the right ram
for it tho. Edit- no it uses floppy Ram, just like @AncientBoi