Version 2017.03 adds an option to automatically prefix event titles based on the associated calendar. The prefix can be specified in the Calendar Properties. Each calendar can have its own prefix.
The prefixes will appear on events in the Day, Week, and Month views. The prefixes will also appear when printing and when saving to a webpage. Calendars can be color-coded, but seeing a prefix can help you more easily differentiate which calendars events are associated with, especially if you work with a large number of calendars, or calendars that have similar colors.