And i can see that some fields are translated, even while browsing the administration pages.

For example on Notification settings > Order update (/en/admin/store/settings/notify/edit/update) the subject and body fields show different content while browsing on English and Portuguese (my two languages).

But Notification > Checkout (/en/admin/store/settings/notify/edit/checkout) does not. The email subject fields always show in the same language. It's like the string there cannot be translated or sumthing.