The pic below shows the tops of four of the original eight half-arches before 2023, which I snapped from the RCT site.
To me, It looks like all eight were severed in the 1914 work when making them detachable. That is my guess when there would be no reason for "the delicate silver wires and strips comprising the structure of the Crown" originally to be "spoiled" in that way from the start.
So what I have been calling the second tier is actually some diamonds (possibly?) added to the blunt tip ends of the intermediate missing half-arches. I do hope you agree on that.
As to whether or not the main half-arches have been shortened I cannot be sure about. It has been difficult to find pics to match the angles from which the crown has been photographed.
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