Dark Souls’ implementation is something special. Censors your name based on the language settings you have in place at the time, voice-over dialogue remains in English. So change your system language to either another language you know, or play it a few times so you know what things are, and then put the most offensive shit in as your character name you like.
Should have used Vim instead, that’s a real text editor. No-one who starts using it ever moves on to something else.