In short, the temperament does not affect the calmness of the biters. If there are action points, they are always engaged in malicious activity
Temperament is the AI's assessment of whether there are enough nests for attacks. The score is affected by the player's losses and killed biters. The more nests, the weaker the impact of losses. The loss counters are reset when the AI mode is selected again.
The only thing temperament affects is the choice of a new AI state (and, in part, on the generated action points - minimum in the range 0.4 - 0.6).
Low temperament usually leads to "siege" mode. High - to direct attacks. Ultra-High - increased chance of "Onslaught" mode with massive attack, double passive points generation, ultra-high points generation for destroying player's buildings. Thus, temperament does not directly affect the difficulty, changing the nature of actions.
An "aggressive" state is possible with any temperament. This is the most harmless AI mode. But it should be said that what is happening on the map is determined not only by the state of AI, but also by the situation on the map
At the moment, temperament takes on a final meaning almost instantly. An increase in the parameter will definitely not have an impact. This parameter is one of the candidates for exclusion from the settings Rampant Fixed