If you are missing these, Steam may try to download them automatically after you change the setting in Steam Properties.
A modder extracted the Localization.txt , ran a find-and-replace script to convert "Vosotros" to "Ustedes," and re-uploaded the mod to the Steam Workshop. Within a week, it had 50,000 downloads. This demonstrates the power of a simple text file to improve the user experience for millions. Call Of Duty Black Ops 3 English Localization.txt