I believe there is a mistake in your (excellent and fascinating) CHIP-8 extensions and compatibility document, relating to reserved memory addresses on a 4k COSMAC VIP; specifically:

This seems to be an extremely commonly cited figure, but I believe it to be incorrect, and that it should be 0xEA0. I have just reported this as a bug in Octo with a lengthy write-up, so rather than duplicate that in its entirety here as well I'll link you to the Octo issue instead to refer to for further explanation: JohnEarnest/Octo