If the error persists, a clean install focused on a single language often bypasses the "build problem".
: Ensure that all three versions of the game (Singleplayer, Multiplayer, and Zombies) are set to the exact same language in Steam. A mismatch between these three can trigger the error. Right-click each title in your Steam Library . Select Properties > Language . black ops 2 sound bank failed to load cmn-root.english