Except that it has been said that Kyle Rayner (you know, that new Green Lantern guy) is from Earth 8. And we don't know for sure that in this megaverse that Superman does not exsist on Earth 5 or not. Your argument is thin but there is no denying the symbolism of the cover is having the card numbers coincide with the Earth number.
Um, you're looking at a total of THREE NUMBERS out of thirteen and claiming that they set a precedence that the other ten don't. Heck, it might be only
two numbers, considering we don't know which Batman that is. Nearly every other number on that page contradicts the rules that you've set in ways that I've already explained so, frankly, it looks to me like there's a
lot denying the "symbolism of the cover."
We don't know for sure whether Superman exists on Earth 5...except that you're claiming you know for sure

.
Kyle Rayner is from Earth-8, but he could not have been a member of the Green Lantern Corps in that universe. Most likely he was called Ion there or another GL equivalent like Alan Scott and the female Green Lantern from the tangent universe. Oa is the one planet that only exists in one universe; the Oan called Krona looked back into the beginning of time and that was what shattered the universe into the multiverse in the first place. That's part of its history right back to the silver age. Sinestro or Hal Jordan or Guy Gardner might exist in other universes other than Earth-1 but they could not be members of the Green Lantern Corps there, which they obviously are depicted as on the cover.
Morever, Geoff Johns has officially stated that Earth-8 is home to "all characters created after Crisis on Infinite Earths." Guy Gardner, as I've already said, was created before then.
Christ, I love being so right.