Hi James,
You can download the latest version Facebook app from here: https://stackideas.com/apps/item/3346-facebook-for-easysocial
The language file for the app should be included in the zip file: http://take.ms/z1JAH
This file will be installed to this location: JoomlaFolder/administrator/language/en-GB/en-GB.plg_app_user_facebook.ini

All of the admin language.

Hey James,
I checked your backend and it seems the language translations are displaying fine. If I'm missing something, perhaps you can provide a screenshot of the page having this issue on your site so I can investigate this? Thanks.

I installed it on my localhost dev today, both the facebook and twitter have the languages missing.

Hey James,
Without the Facebook app language file in the backend, this is how it looks like(http://take.ms/wo05f).
To double confirm, does the issue persists even after you reinstalled the app and also made sure the language file is in place at JoomlaFolder/administrator/language/en-GB
Can you also provide a screenshot of the page having this issue and also the language file if you have them at the file location mentioned?

That is correct, the file is not in the administrator's language folder.

I just manually uploaded the language file and all is fine. But something must be wrong with the package if the installer isn't distributing the language file itself.

Thanks for reported, I've checked again from those Facebook and Twitter installer xml file, it seems like we didn't include those language file, I will log this into our issue tracker.