Could you check if it works now? Our R&Ds have failed to reproduce the problem. Google Home works fine under our test with your devices and several other devices.
It could be caused by Google service outage. We noticed that you tried to use Google Home on 04/21, on which day Google Assistant service had no response issue similarly. Few hour later, Google had fixed the problem and everything went back normal.
If still not work, could you please try to unlink your Netro account then link it again? We will send you email about the details and proof that it should work now. You may see watering schedules lasts for few seconds on the schedule page on your App, don't worry, it's caused by our internal tests.