After leaving the letters, Lucien and Philosopher quickly left Morning Star's place and disappeared in the darkness.
In fact, as this was not the first time that the Inquisition dealt with Professor, the Inquisition indeed considered the possibility that Professor was playing the same trick again—the purpose of Professor showing up in Aalto again was to find the spies in the circle of magic, so what happened to Fire Wolf would happen again. Therefore, the inquisition was ready to put several of their spies hiding in the magic groups under this risk. After Mercury and the other apprentices told more magic groups the information about the Congress, the spies in those groups would also report the message to the Night Watch.