Does the calendar support European date formats?
Absolutely. DayBack will pickup your browser's date and time format settings much as it picks up your language.
Specifically, the date formats the calendar displays in the calendar navigation headers and the mini-calendars are based on your computer's language setting. If you are in an English-speaking country outside of the US make sure your language is set to that specific region. For example, you would set your computer language to English UK if you were in the UK, or English Canada if you are in Canada. This will ensure that you get the appropriate date formats for your region.
When you're editing an event in DayBack's popover (the small window you see when clicking on an event), you may want to use a different date format than you do in the calendar's headings. You can override what DayBack suggests as the editing date format in Admin Settings where you'll find a section devoted to date formats in the left-hand sidebar:
DayBack does need to know the native date format for your FileMaker file, however, and you set this when you're configuring your FileMaker Server as a calendar source. You'll see a field for the file's date format and you can enter something like:
If that's not working, scroll down that settings page and click the "Test Source Settings" button. Once the test resolves click "Show Test Details" and look for the "Fields available" section near the end. You should see a value for the date format like this:
That's the format to enter into your server's settings. =)