In Chiron's memory of this world, The Night Mistress did not die so early. In fact she had waited and prepared well before executing the plan for the revenge of her mother on the holy church.
She had executed this plan during the Great War, and then, she had been responsible for a great loss to the Holy Church, as well as killing the Thalus who had been the finger of solitude that had ended her.
It would seem like this time around, the Night mistress believed that she had a ripe opportunity and did not want to let it go. However, it ended up becoming the reason for her downfall.
After all, Over 50 years of planning was better than a few months.
But Chiron did not blame her for this. Hatred was an ever uncomfortable feeling and it must have kicked heavily at her heart.