Hi Jos,
The official name of our “pro” addon is actually Events Calendar PRO which is why the plugin slug is a little different from that used for The Events Calendar.
For consistency and to enable a smooth upgrade experience for existing users, I’m not sure we’re likely to change the deafult directory name at this point (though if you feel strongly about it you are welcome to post a request on our UserVoice page – this would help us to discover if others also have strong feelings about this).
At any rate, I’m glad you were able to locate the translation.
Thanks again (and I’ll now close this topic – but please don’t hesitate to create new ones as needed if any other issues arise) 🙂