I cannot see anyway that celebrating their spit from the Catholic faith is going to help with creating unity with Protestants. Even Protestants can understand that from the Catholic perspective the reformation was a tragedy for Christendom. It is inherently contradictory to say that unity within the Church is a good and necessary thing and to celebrate a breakage in the unity of the Church that caused so much chaos and destruction.
Protestants aren’t freaking out about “unity”.