Go into Control Panel > Regional and Language Options. Change the date format to d/M/yyyy.
Now go into Logos and bring up a calendar-based resource such as a lectionary or daily devotional.
Attempt to enter the date in d/M/yyyy format, and it doesn't work.
For users in Canada, this is marginally acceptable, since US and European date formats are used interchangeably. But for users in the UK and Europe and other parts of the world that use day-first date formats, I suspect this will be frustrating.
Logos should respect the date format in the user's locale by checking what they have set in their control panel.
This probably goes for how dates are displayed too. The date display in Logos seems to always be January 1, 2010.
But some people prefer 1 January 2010.