Does the calendar support European date formats?
Yes. Most of the dates in the calendar will reflect the date format set up on your computer without you having to do anything.
The only exception to this is the big white-on-blue display in the calendar header. That date is a calc field and we've hard coded the date formats into the calc so we could display things like "Week of..."
You may need to change the formatting of that display in the calc by editing the field definition for CalendarInterface::DateDisplayCalc though we've tried to teach this calc about commonly used date formats.
Cloning the file
Note that you can always make a clone of the file in order to reset the file's location information.
As soon as you open that clone the file will think it was created with your date formats as its default. (Complete's Upon Opening script recreates the interface records the calendar needs to operate, which are deleted as part of cloning.) Remember, cloning the interface file (SeedCodeComplete.fp7) doesn't erase any of your data, though you'll need to clone the data file in order for this to truly reset all the date formats in the solution.