Thank you for your answer.
Here are some clues, to get the string translation to work.
http://wpml.org/faq/getting-string-translation-to-work/
The problem is I cannot find where is the “slogan” set in the templates.
Now I am facing other problems that has to do with the slider translation.
As I cannot understand how the coding work in your theme, I am not able to find the way out.
You might want to explain me a little bit how is the theme structuring the coding, to see if I can find my way on my own.
Thanks
Miriam