Translation is not done completely

Translation is not done completely

What I expected to happen was...:
The death message was supposed to be translated like "Player a été tué" or "Player quitté les confins de ce monde"

What actually happened was...:
The text just appeared untranslated: "Player was killed" or "Player left the confines of this world"

Steps to Reproduce:
1. Change the language to something else than English
2. Type /kill with cheats on or leave the world border