While the important thing to understand about the Aqara Motion Sensor's lux reports is they only happen when motion is detected, it is equally important to know that the lux report message is received by the hub some milliseconds before the motion detected message.
This sometimes results in the motion detected event occuring before the lux value event (due to the timing of separate instances of the driver code running for each message received). So, it's possible that an automation triggered by motion detected will be making decisions based on the previous lux value (since the new lux value event may not have occurred quite yet.) So it's best to insert some kind of short delay before the automation / rule evaluates whether action should be taken / not taken based on the lux value.
First off, the Aqara Temp-Humidity Sensor is designed to report Atmospheric Pressure in an open-air environment. So it may or may not work well as a sensor for measuring air pressure of an HVAC system. I have read of one person using it that way, @brianspranger, but I can't seem to find his post on the ST forums about it at the moment.
Otherwise, as far as frequency of pressure (and temperature and humidity) reports goes, I'll repeat what I've stated in this post:
Here is the best documentation I have found, located in the GitHub repository of the parent company Lumi United Technology's:
When the temperature and humidity sensor detects temperature changes over 0.5 degrees or more than 6% humidity change, a report will be sent. The atmospheric pressure value will be sent along with the temperature or humidity report. The Temperature and humidity sensor also reports the current temperature, humidity, and atmospheric pressure values during each heartbeat.
Note: when they say "temperature changes over 0.5 degrees" they are talking about changes in degrees Celcius.
Despite what Lumi states above, in my experience, the reports are not as consistent as would be expected. I have seen the sensor wait to report on temperature changes in excess of +/- 5° C. Also, temperature changes seem to have priority over humidity changes. So the sensor seems to sometimes wait for a +/- 5°C temperature change before sending a report, even though humidity has changed more than +/-6%.
However, changes in pressure values alone do not result in a temp/humidity/pressure report being sent. The pressure value report just "rides along" for reports sent when either the temperature or humidity has changed past the above mentioned thresholds.