Using version 6.1.2 of plugin.
Russian .po file contains
Please enter your username or e-mail address. You will receive a new password via e-mail.
and theme-my-login\includes\class-theme-my-login-template.php contains
case 'lostpassword': $message = __( 'Please enter your username or email address. You will receive a link to create a new password via email.', 'theme-my-login' );
so the translation is broken at this point.
If someone has such problem - simply copy the text from one place to another to make texts identical.
PS: jfarthing84, thanx for the great plugin! :-*