Carlos,
On your home page, I see multiple inclusions of the Facebook Javascript library (all.js) within the HTML. The Error Checker built into JFBConnect should be calling that out, and we'd recommend disabling any other Facebook extensions that may be enabled on the site to test with. It's possible that's where the problem is coming from.
Regarding the About Me not being filled out and not showing a problem, that's a template issue. When Joomla's validation (which we use) detects a field that is not filled out, it adds the class "invalid" to the input that wasn't filled out. You can add the following to your CSS which should highlight the problem fields:
.invalid {
border: red 2px solid;
}
Finally, for the language, JFBConnect uses language files for all of it's front-end views. We distribute a es_ES file that should be used. The only reasons that I can think of that it isn't used is if you have the Language Filter plugin enabled on your site. That plugin will detect the user's browser language and then let Joomla know. We respect that setting and will load the proper language file then. Can you check if the System - Language Filter plugin is enabled? If not, do you have any other language extensions installed on your site?
Thanks,
Alex