Thanks for your answer Chouby, and sorry for my late reply.
1. I can't find the definition of the function you say. I'll ask to the authors of the template. In the meanwhile, supposing that "top-bar-text" and "copyright" are the correct names, what should I do? I put a file called wpml-config.xml into /wp-content/polylang/ containing this:
<wpml-config>
<admin-texts>
<key name="top-bar-text" />
<key name="copyright" />
</admin-texts>
</wpml-config>
but as far as I can understand nothing seems to change. Is this procedure correct and complete?
2. The css rule works fine, since I'm using the language switcher in the sidebar. Anyway, if I check the option to hide the current language and if that specific post is not available in other languages, in the sidebar I'd see the widget's title without any flag. Is it possible to completely hide the widget if there is not any other language except the current one?
Thanks for your support
Daniele