Hi,
HikaMarket uses new translation keys in general.
So you can use the key "ORDER_STATUS_CREATED".
If the translations is not found, HikaMarket will try with the key "CREATED".
And if still no translation, it will use the "created" word.
About the email, I guess you can replace
'ORDER_CHANGED' => JText::sprintf('ORDER_STATUS_CHANGED_TO', $url, $data->mail_status),
By
'ORDER_CHANGED' => JText::sprintf('ORDER_STATUS_CHANGED_TO', $url, hikamarket::orderStatus($data->mail_status)),
In order to translated the mail_status which is the order_status value in the raw (not translated).
Regards,