This is the po file management module that is used on http://orchardproject.net
In order to be able to upload new translation files or edit existing translations, you must have the corresponding permissions. I recommend creating a "Translator" group and assigning people to it. Furthermore, to edit a specific culture, you must belong to a group whose name is the culture. for example, in order to edit the French strings, you must have the translation permission and belong to the "fr-FR" group.