But isn't the question about constitutional marriage a slightly different affair from whether the COE considers marriage for the normal Anglican? It's an extra layer of definition that really only applies to the monarch's marriage, and not even, really, the POW.
I do think it's something that still needs sorting out. But I think this is exactly the sort of detail that monarchies are best able to adjust from generation to generation and it's only logical for this marriage to be the one that brings this set of requirements more up to date and in line with the general definition of marriage in the COE and in broader British society.
But also, I expect it's in this level of fine detail that Charles will "modernize" the coronation ceremony when his time comes. I expect to see a lot of small tweaks here and there to streamline things, but it seems laughable to me to think that major points of continuity from generation to generation like the use of coronets and peer robes, etc. would be altered.
At this point, the value of a monarch is to be a visible and tangible link to the particular traditions and history that make his or her nation special. In the UK, one of the major points to highlight is the fact that the central traditions date back to the Medieval Era, and that there's been an unbroken line of monarchs on the throne since Charles II, so the highest levels of pomp and circumstance, of which a coronation is the highest, will always have some level Medieval and Baroque overtones (those robes, for instance). And, quite frankly, the most cost-effective pomp to include is the kind that the monarch himself doesn't have to pay for, such as other people's fancy-pants attire.
I'm willing to bet the place for big changes will be the activities surrounding the actual coronation, such as the procession to and from Westminster. When everyone and their brother can see all the details of the ceremony in high def on their phone, there's not really such a need to turn the ride back home into the most overwhelming possible impression by parading of all the fancy carriages in the realm. That's the kind of place where I expect Charles to really pull back and make it be all about his own family (he and Cam, W+K and their kids, Harry and his wife, if he has one by then).