I was up early this morning while the system was still watering and popped open the app to see how far along it was out of curiosity.
The top simply says "Watering" with a start time. There is also no end time listed even though the controller knows it should run for 184 minutes if the whole event completes and says so in the notifications sent just before it is about to start.
The individual zones say "Watering Now" and list the total scheduled time for that zone beneath it. No indication of how much time is left or some graphical circle reducing its arc.
I hadn't thought about it before, but it would be nice if the calendar shows historical watering events. Maybe change from green water drops to a full blue water drop to indicate a complete event took place, a broken blue water drop if the event partially ran, a blue water drop w/red slash around & through it to indicate a skipped event (Rain skip, rain sensor, whatever...), a little rain cloud for some precipitation (but not enough to trip the sensor).