Displaying date under title

Yes, the format of the widget can be altered using placeholder tags, or template file: http://docs.wp-event-organiser.com/widgets/events-list/

To format the date/time of an event you can use eo_get_the_start(). You can put in literal text, such as à by escaping it with a backlash. E.g.

echo eo_get_the_start( ‘jS F Y \à G:i’ );