The homing pigeon cage is your task for my younger brother, and the assassin contract is your own task! These tasks are also collected in carrier pigeon cages, but these carrier pigeon cages are fixed. Before doing the task, it is an assassination symbol, and after completing the task, the icon will become a homing pigeon cage. Every time you make an assassin's contract, you have to get a new one from Barto Lollio's wife in the barracks.
Less than 90% may be because the previous tasks were not completely synchronized. Have you completed the guild challenge?