One area in phase that you is always left out is the phase of the midrange cone during playback. If you look at the Wilson midrange it’s out of phase as it’s not a true pistonic driver.
I’m sorry but this is misinformed.
The correct polarity of the driver (which terminal is attached to + or - wires) has nothing to do with "true pistonic" motion. We assume they’re all pistonic in their operating range. The reason a speaker designer may flip a driver is to phase match the driver above or below it. The output’s phase angle is related to the rolloff. This flip ensures optimum frequency response across the crossover region. In fact, using positive polarity would create a deep null.
With traditional (non time-aligned) 2-way speakers, flipping the tweeter relative to the woofer is quite common. With three, having the mid-range flipped relative to the woofer and tweeter is.
The angle of the speaker’s baffle, the acoustic center of a driver and the crossover slopes all contribute to these choices. "Pistonic motion" does not.
Lastly, if we are talking about the sliced paper cone drivers Wilson uses, those are some of the very best sounding mid and mid-woofers in the world. I have them in my own speakers and many high end manufacturers have turned to them as well. They are amazing.