(1) The firmware limits the turn on time to maximum of 16 hours. So if you observe a valve is stuck for more than that, then it’s not a software problem — it’s likely due to hardware or mechanical problem. For example, if you power OSPi using a DC power supply (instead of 24VAC), that will result in valves open but then cannot close properly. It could also be due to some sort of mechanical problem of the valve that kept it in.
(2) for notifications you can make use of the IFTTT notification feature that’s available in the latest firmware (2.1.7).