This question was initially about Russian PC version of Titanfall, available in Russian Origin store.
It appears that there exists a Worldwide PC version of Titanfall for which Origin has posted a way to change language.
Tech support said that Russian users can only buy Russian version of Titanfall (both normal and Deluxe editions) and that they will not have any other in-game language available. They also offered me a refund, which I accepted.
I'm living in Russia and I recently pre-purchased Titanfall from here. My version doesn't have an option to select game language other than Russian.
Russian version has awful localization, many mistranslated technicalities and poorer game UI fonts than its English counterpart. Titan's on-board AI voice is pretty lame. The campaign briefing lines are cut off to fit the English files' length. Voice actors took liberty to change a few things to their liking. Audio effects like reverberation, echo and such are distinctively more basic. Overall audio quality is much lower, which greatly hinders immersion.
When I was playing open beta, it was all in English and considerably better. The game also doesn't support Russian characters so everyone is using transliteration in chat.
Switching Origin UI language to English didn't change the game's language. It's still all Russian.
How do I change Titanfall UI and audio to English?
Also: the support person didn't explicitly say tampering with localization files was against any rules or policy, so this may or may not be okay to do. Gotta find some hard info on that.
Although, adding launch parameters
-language "english" in case of Russian version does not help. Players with other versions report that it does help.
As can be seen during game installation, the sound files alone take up about ~33 GB of disk space, and according to Origin's solution to Worldwide PC version, these files contain localization for every language available. It's just the rights to access them depend on version.
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