I didn't translated the keywords field. It's a native Joomla! field. If you read the extension description:
"Showtags is a Joomla content plugin to show article tags in category or article views. Plugin is based on article meta-keywords"
This extension uses article meta-keywords as tags. I understand that can be something confused if you are not familiarized with Joomla!.
I'm sure that your comment will avoid the same confusion to others. I'll include this into the documentation.
Thank you for your time reviewing/giving feedback.