Hi Marc,
Take a look at the technical documentation of
Cookie Control. If you want to just change the text of the buttons, you need to edit the "t" property (look for the "Customising Text Messages" in the documentation).
If you want to add new translations for the button texts, you will need to edit the "locale" property, to add the languages you want, and then add the texts in the "locale_t" property. Again, you can see how you can use these two properties in the technical documentation.
Regards,
Gerasimos