I've created a thread on DIYaudio website. It's basically the same but it has a few extra stuffs.
https://www.diyaudio.com/forums/multi-way/345669-exercise-converting-speaker-time-phase-coherent.html#post5984990
https://www.diyaudio.com/forums/multi-way/345669-exercise-converting-speaker-time-phase-coherent.html#post5984990