You didn’t miss anything. There is no master list of systemwide event history.
If you have an On Duty sensor that trips an HMS alarm, it will show that sensor in the HMS activity Hx, but only if it trips an alarm. They will not show when Disarmed or if the sensor is Off Duty
For what it is worth, I don’t trust the monitoring event Hx. Look at the times. How did I set the alarm off by opening the back door AFTER the alarm was cancelled and disarmed 1 second later??? Would think the door opening would have to be first. Time stamps are off.
Also included in your list should be Rules Hx, which is found in yet another place.
This has the makings for a great Wishlist request. Fortunately, another user has already thought of it.
Here is the Wishlist topic. You can go there, vote at the top, and add your ideas at the bottom. Also be sure to like any of the idea posts in the topic.