Thanks to fdzkuz, ImHuman API and its wordpress plugin speaks Russian now. WordPress plugin owners who wants to use the new language for their tags, here are the steps for version 0.0.9, latest stable one.
Open the Editor and select Imhuman.php to edit.
Go to Line 149, Where you will see
$lang = array('en'=>'ENGLISH','fr'=>'FRENCH');
Change that line into
$lang = array('en'=>'ENGLISH','fr'=>'FRENCH','br'=>'Brazilian Portuguese','ru'=>'RUSSIAN');
Save your file. Go to your plugin settings and update your language choice.