Erro Google+ : COM_JFBCONNECT_UNABLE_TO_RETRIEVE_USER

That message means no information about the user is being returned from Google. That could be caused from a few different causes:
* The user doesn't have a Google+ profile. In this case, make sure you've enabled the "Use OpenID if No Google+ Profile Exists" in the Configuration -> Google section. You'll get less information about the user, but they should still be able to authenticate.
* Turn off SEF URLs and disable 3rd party search engine extensions. Sometimes, the cause issues by altering the JFBConnect URLs. If this fixes the problem, let us know, as we can usually help you to re-enable these extensions.
* Disable caching in Joomla. Test if that works and, again, we should help you re-enable caching.

Let me know if any of those suggestions help or not and we'll do what we can to get you going.

As for the language string itself, it's located in the /language/en_GB/en_gb.com_jfbconnect.ini file and *should* be in our other language files. There are a few strings missing from other language files that we're working to correct. If you are using a different language, let us know what it is so we can investigate further.

Thanks,
Alex

Andy,
Glad we could help get you going. If you run into anything else or have any other questions, just let me know.

Thanks,
Alex