Yes we missed that term to pass for translation. To fix it replace line 14 like following.
echo ' - <a href="' . Language::get_url('admin/upgradetodealer/') . '">upgrade to dealer account</a>';
echo ' - <a href="' . Language::get_url('admin/upgradetodealer/') . '">' . __('Upgrade to dealer account') . '</a>';
Then go to “Settings” -> “Language” from admin panel and click on “Translate” button next to language. On opened page click on “Rebuild translation terms” button. This will search script for new terms and add them to message.php file. It will also remove unused terms from message.php.
After the term added for translation click on “Display empty values” or search term using search field, and write translation to text field next to term. Then save changes.
Thank you for reporting, we added it to script and will be available with next release.