[How-to] Force the DS/DSi games language with an AR code

Since it doesn't seem possible or easy to modify the Japanese 3DS/DSi to display any other language than Japanese/English for the DS/DSi games, I searched a way to force them to launch in the languages I want.

I first tried some hacks on the 3DS/DSi, or modified the files of my games by dump and unpacking them, but no solution works well.

So I searched an Action Replay code that allows me to override the firmware language, to force my games to launch in the language I want.
I found a lot...

[How-to] Force the DS/DSi games language with an AR code