Prestashop 1.6 don't load language files

[gainza]

Hi
 
We have detected that the web don't load languages ​​or translations of the theme. I know that don't load the translations because I have tried to change texts both in the backoffice's translation manager and directly in the php file and doesn't change anything, neither if I change texts of the theme language.
 
In this way all the texts that depeden of the theme appear by default in English and when selecting language don't load the translations.

I am totally lost and we have not made any changes in principle that have to affect this point.

Any ideas?