The problem is in the upper button to change language that uses the dropdown code from the BootStrap 3.X library that uses the JA FOCUS template.
If you click on the main page built with JA Builder, I can't change the language.
On the other hand, if I go to any page like the one indicated that is not made with JA Builder, it works and you can change the language with the upper button.
After checks I have detected that JA Builder proves that dropdowns of Bootstrap 3.x stops working. I've checked it by replacing the official page codes that work correctly and it's the same problem. Must be some problem with the Javascript code, I guess. I even put it in other areas of the page and the problem is the same.
It works (I can change the language): https://rutadelvinoyecla.com/es/blog/participantes-del-ii-concurso-de-intervencion-de-barricas-al-aire
It DOES NOT work (I can't change the language): https://rutadelvinoyecla.com/es/