I have not found a way to report on calendar owners - or which dashboards a calendar might be added to. But both would be super helpful!
We've recently had 2 users leave our instance who had created several of our calendars. So before deactivating those users I had to figure out which calendars they created, who they had shared those calendars with, and which dashboards those calendars were on... Then copy each calendar, reshare it, and replace it on dashboards.
I was able to limit which calendars I had to look at to see if each user was the owner by logging in as them and only checking those calendars they had access to.