So the problem is that component's
language var is being changed with Joomla's
language var. Here is the dump of
data var of IInput:
[data:protected] => Array
(
[option] => com_ctransifex
[task] => download
[language] => ru-RU
[Itemid] => 1178
[lang] => ru
)
Funny! The only workaround I found is to get language var directly from get. So I've changed
$input = JFactory::getApplication()->input;
to
$input = JFactory::getApplication()->input->get;
And now it is working
Interesting that on another website everything is working fine without this change...