If you use the Plutonium client for BO2, they provide built-in support and verified assets for language switching. If you'd like, I can help you:
To successfully convert the game, you need a verified set of files that match the current version of the game. A complete pack usually includes: 1. The Localization Files If you use the Plutonium client for BO2,
Simply changing the "Language" value in your Steam settings often results in a "Fatal Error" or a black screen. Essential Files for the English Language Pack The Localization Files Simply changing the "Language" value
If the game updates, your language pack may break. Always keep a link to the pack provider to download updated English assets. Where to Find Verified Packs The safest places to find these packs are: Where to Find Verified Packs The safest places
Activision often released specific versions of Black Ops 2 for the RU/CIS market. These versions are significantly cheaper but are hard-coded with Russian language files.
The Russian version uses common_ru.pak . You will need the English equivalent ( common_en.pak ) located in the main directory to hear English dialogue and announcer voices. How to Install the Language Pack Safely
Guide you on setting up the for a better experience.