Hi alehache2005,
Thanks for your note. Our calendar is not completely compatible with WPML, which is why you are having trouble. You can set the title of the widget on your widgets page. However, it is not a translatable string. You’ll need to decide what language you want the title in, or have it as Calendar/Calendario. I apologize for the inconvenience.
We would like to integrate better with WPML in the future and we have a UserVoice thread for it. Adding your vote there will also allow you to stay updated as we work on it.
Best,
Leah