I was going to say that the difficult part would be to convince them they were running on standard time. Have you asked them if this is possible or is it one of those "talk to the hand" situations. As far as the times of day, the website does have the one window which has all the gory detail on when zones start and stop but I don't know how far back in history that data is saved. I tried going back in history in that window and it's pretty arduous. Of course all this might be wasted effort if their attitude is "we're right and you're not regardless of what data you've got". I agree with Robert that this probably wouldn't stand up in court, but who would ever want it to get that far.
If you really want the history data, I'd ask the Rachio staff if they could pull it for you.
Thanks for all your effort in Patch Watch, I've followed your advice for years. Good luck.