I think I know whats going wrong.
The update rule crashes the whole logic.
For example pimatic seems not to recognize when the thermostat is on boost mode. Then the rule is triggered and changes the setpoint by 1°. That kills the boost mode.
If pimatic would know about it, I could check it via rule and only update when it’s not active.
The rule is needed to get the temperature measured by the thermostat. As it is only published on changes.