I have all translation files .po and .mo at the language plugin folder, added a new language files "attachments-pt_PT" .mo and .po, but it still shows the texts in english.
(E.G.) String "change" mentioned at classes/class.attachments.php at lines 903 and 1374.
My language files pt_PT has the translation string but it never get translated.
Also using a multilingue plugin, Polylang, not sure if it conflicts, I've performed the test of deactivate it and check if the "change" string gets translated and no luck.
Using WP version 3.6.1
Attachments version 184.108.40.206