triggerCondition only evaluates the condition on very specific limited cases, it is not a magical “observe and re-evaluate whenever this arbitrary lambda’s return value might have changed” system.
I think triggerCondition is re-evaluated when any signal which is connected to the script behavior (and thus also causes a OnSignal call) is triggered, not sure if there any other cases.
Now I also remembered that there is a evaluateCondition() method which can be used to trigger re-evaluation of an active triggerCondition within the script’s OnRun method. It can be useful when a script is listening to events other than signals.