On the page that is shown in English, in the HTML, there is the block of code below. This code is re-loading the Facebook Javascript library from en_US, which means that the social widgets would be in English. Additionally, this code will likely conflict with other features of JFBConnect, like the Login with Facebook feature, if you're using it on that page.
js.src="http://connect.facebook.net/en_US/all.js?xfbml=1&appId=348576805217686";
You'll need to determine what extension is adding that code and prevent it from doing so.