To select which language to use in the form you need to add this tags to the code of the form:
<div style='display:none;'><input type='text' id='feedback-language' name='feedback-language' class='feedback-language' placeholder='Select language (en/ru)' value='en'/></div>
If you need English - then leave value='en'
. If you need Russian - change value to 'ru'.