i know is not the correct way, but i couldn't find the correct anwser.
My site is in spanish, front and back, so it is suposed that if there's a pack in spanish in Language/ the component should use it.
What i did was change files es-ES to en-GB and i put the files in the en-GB directory and it worked.
I hope this could be usefull to somebody and if there's another way, please, let me know.