In recent years, Steam and Activision updated the game to treat the censorship as a regional license flag rather than hard-coded files. If you own the game on Steam, you may not need to download external files.
Launch the game and check if the "Zombies" option appears in the menu. The game text and audio will likely switch to English. Safety and Multiplayer Guide :: Uncut Patch [GER] - Steam Community cod waw uncut patch