Hi again Antonio,
I would love to help you out with this.
Basically, the language files packaged with our different plugins might not always be 100% up to date.
But the good news is that you can always get the latest files for your language here: http://translations.theeventscalendar.com/projects
Once you download these files, you will need to drop them in the language folder of the plugins.
You might also need to rename them slightly to match the name found in the language folder of the plugins.
The strings you are looking to translate are actually part of the Event Tickets Plus plugin.
As an alternative, you can always use the following method: https://theeventscalendar.com/knowledgebase/change-the-wording-of-any-bit-of-text-or-string/
Let me know if that helps.
Have a great day!
Geoff B.