I think you are grasping at straws when you are looking at these home speakers. The whole point of what they are doing is aligning the voice coils of the speakers to be equidistant from the listeners ear. If you put the tweeter on the exact same plane as a mid and a woofer, the tweeter response time will arrive at your ears slightly faster than the mid(s) and especially the sub(s).
This is true time correction from a mechanical standpoint coming from the hypothesis that the sound originates from the coil and radiates out. Considering the speed of sound is somewhat slow, it is noticeable and that is why the $$$ manufacturers do it.