Sorry for the high number of feature suggestions. This is the last one for now, I promise...
In your blog I noticed that you can "create and start a timer". I have to say I was shuddering a bit when I saw that because it's very much developer language. I understand that you want to support creation and starting of timers as separate actions, but it's a concept which is probably not very intuitive for people other than you and me (read: non-geeks).
How about supporting something like this:
(1) Computer, please remind me to call Stephanie in 10 minutes.
(2) Remind me to start cooking at 11 a clock.
(3) Please ping me at 10:20.
(4) Please notify me in 10 minutes.
I'm not sure how difficult it would be to actually fully understand (and later repeat) stuff like (1) and (2). Probably that's too much StarTrek for now? But maybe you could still understand (1) and (2) and create (and start) a timer for that and then just do the notification without saying what it was for. Or maybe if I then ask "What was the notification for?" CastleOS could replay the recorded audio that created the timer. That might be useful if the timer was created multiple hours or even days earlier.