Hello JCB
You can create your own help files in Dutch. This way you can tailor the system, so you can give your users instructions that matches your use of the calendar.
The calendar can be set up for many purposes, and therefore the existing help-texts are very general. You can make a text that matches exactly the purpose of your calendar.
See here for more information about the help files : http://calendarforum.dk/context-sensitive-help.html
Kind regards
Schwartz