Try to stick to one language.  The site has defaulted to spanish since before I migrated it over to your hosting.  I noticed that the taxonomies and some content types have been changed to spanish even when I am in english.  You'll have to stick to one language, either define them in spanish while you are IN spanish or define them in english while the language is set to english.  THEN you can translate them to the other language.  If you have a translation string  in the translation interface that is backwards:

Foros - English

empty - Spanish

Just delete that string from the translation interface by clicking on "delete" or "eliminar" and go back to the area where it was originally defined. So if it was a taxonomy term, delete the string from the translation interface, and go back to the taxonomy page (in spanish), and open up that term.

Then go back to the translation interface and you will see the newly created term

Foros -> spanish

empty -> english