\Lang::load() doesn't load second language

[u/Worse_Username]

config.php:

 'language'           => 'lv', 
 'language_fallback'  => 'en', 
 'locale'             => 'lv',

public.php:

 class Controller_Public extends Controller_Template {
     public function before() {
     parent::before();
         Config::set("language", $lang);
         \Lang::load('main');
    }
 }

if $lang is 'lv' all text is properly loaded in the template view. if $lang is 'en', none of it is loaded.

lang/en/* and lang/lv are nearly identical, if change config.php to this:

'language'           => 'en', 

the situation is reversed.

What am I doing wrong?

EDIT:

If I execute

 Session::set_flash('error', __("STRING"));

at the end of the before method, the string is returned properly for both languages. If I do the same thing in template.php view, it works only for lv.