That they largely got right (once I was looking at the correct conversion table).
ie: for well protected trad routes
7a+ - 7b routes would be E5
7b+ - 7c routes would be E6
7c+ - 8a routes would be E7
8a+ - 8b routes would be E8
8b+ - 8c routes would be E9
8c+ - 9a routes would be E10
9a+ - 9b routes would be E11
9b+ - 9c routes would be E12
This table is pretty much spot on from E5 to E8
I hesitate to prolong this discussion, but here goes ...
I would see this set of conversions as spot on for only a rather small subset of absolutely bombproof single pitch routes. Outside of that very specific genre of routes the ranges are too high, too narrow, and don't overlap, as they do in reality.
If the aim is to construct a more 'linear' version of E grades then I think that is doomed. In my view, the whole point of E grades + technical grades is their flexibility, not their rigidity.
This is also all rather abstract when we actually use grades in context. Even if we simply have a picture with a line drawn on it and no description, when we are actually stood beneath a crag we take in a range of visual clues that help us make sense of a combination of letters and numbers on the page: does the rock look solid; does it look compact and hard to protect; how tall is the cliff; how steep; are the lines obvious or hard to read, etc. etc. Of course, having a guide book description adds even more information.