Cita: How do I display the Like button in different languages?
If you are using the XFBML version include the language code when you instantiate the library. Replace ‘en_US’ in this line with the correct locale code:
'//connect.facebook.net/en_US/all.js';
If you are using the Iframe version include a locale parameter with the proper country code in the src URL. Example:
src="http://www.facebook.com/plugins/like.php?locale=fr_FR&..."
You may need to adjust the width of the Like button to accommodate different languages.
Vamos, en resumen, que hagas lo que estabas haciendo, cambiar en_US por es_ES, el error no tiene nada que ver con Facebook, revisa tu código. La versión en inglés si funciona?