JFBConnect contains language files for English, French, Hebrew, Chinese, and German. If you can't find them in your Joomla language directory, you should be able to find them in the JFBConnect component zip file.
If you'd like to test whether the strings you want to change can be in language files, simply go to Global Configuration and the System tab and enable Debug Language. This will put little dots around text that can be translated. I'm unsure why the languages aren't working for you out of the box, this is not a common issue, but if you'd like us to investigate further, feel free to PM us a super admin account for your site.
Thanks, and good luck