This is the registry for Far Cry 4. You can use this to change the language of the game.
After placing the game files in place and then using this registry after UPlay detects it you must run this command:
"C:\Program Files\Uplay\UplayService.exe" -upc_uplay_id 420 -uplayservice_run_install_script -upc_language en_US
To complete the install, otherwise UPlay will not let you launch the game still as it will instantly fail patching.