I want to fill the title field when adding an event with the calendar name. Maybe it is possible to add a button to do so or just ask for it when I want to save the event without filling the title.

I manage my shift schedule in the calendar app. Therefore, I have a calendar for each shift type: morning shift, late shift, night shift, and free. The calendars have different colors, so, my shift schedule is color-coded in my calendar app. Every day has one of the for colors for the shift types.
However, I have to add events to those calendars. When I add the events, I have to enter a title. The title is just the name of the calendar, i.e. the shift type. Entering it again as title is time-consuming.