The is a community-made (or extracted) collection of .dat and .fat files that manually overwrite the region-locked language assets with the original English ones.
Far Cry 4 uses a hidden pointer file. Navigate to data_win32 and look for a file named localization.lang . Open it with Notepad. If it says ru or pl , change it to en . Save the file (if Windows denies permission, copy it to desktop, edit it, and paste it back). Far Cry 4 English Language Pack