It should be possible to Rename DAVdroid calendars. I am using quite a few calendars and unfortunately, the name of many of them is just “Calendar MyName”. Since I can’t change that when adding the calendar to my system, I now have a lot of calendars named “Calendar MyName” in my calendar app, which all synchronize perfectly, but are hard to keep apart. By temporarily changing my name in the system they synchronize with I can change the name that will be shown, but I don’t have access to this setting on all machines (since obviously, my name usually doesn’t change often).
Obviously, the different calendars still have different colors, but it would be easier to differenciate if I could rename the calendar before adding it to my system. In the synchronization settings, it is much easier to differenciate, because I can use a custom name there. But that one is not shown in the calendar app itself.