If you’ve ever fired up Assassin’s Creed Syndicate only to find the menus or voices locked in a language you don’t understand—often Russian in certain regional versions—the localization.lang file is your best friend.
For a safer method that doesn't involve editing files, you can change the language directly through the Official Ubisoft Support interface: Open the Main Menu or Pause Menu. Select Options. Go to the Sound or Gameplay tab. assassin 39-s creed syndicate localization.lang english
You only need to manually mess with the .lang file if: If you’ve ever fired up Assassin’s Creed Syndicate
Download the patch and copy the folder into your game directory. Run patch.bat and wait for the "PROCESS COMPLETE" message. Manual Cleanup of Non-English Files: All UI text strings (menu options, HUD prompts, tooltips)
.wem or .bnk audio files for English voiceovers).