Multilingual problem in mailchimp_lists.module

I could't translate these three labels:
Email Address:
First Name:
Last Name:

I change this lines:

$form[$wrapper_key]['mergevars'][$mergevar['tag']] = mailchimp_lists_insert_drupal_form_tag($mergevar);

to

$to_translate = mailchimp_lists_insert_drupal_form_tag($mergevar);
$to_translate['#title'] = t($to_translate['#title']);
$form[$wrapper_key]['mergevars'][$mergevar['tag']] = $to_translate;

also I try translate profile fields from Account setting, but i didn't work. I had i18n enabled.