The chaos in Sonic revisions, it's like this never ends
The explanation is on the blog itself, maybe I could put in more information to talk about how the Cosmic Intestate exists across all universes, but I was saving it for my blog about cosmology, but it was never created due to my abandonment of the franchise by here (although I usually answer when it's related to something I created, and this is one of these cases).
Anyway, the scans are all on my blog with the explanation about them.
He would just need to travel through the, y'know, interstate itself to get to each of those universes
And the interstate exists in the universe itself. See in
the scans, the road connects the universes, planets on these universes, literally anywhere. If you want to go somewhere, you must leave your planet and physically move where you want to go. There will be portals that take you from the "dimension of the Cosmic interstate" and leave you in the very dimension of the universe you are in (Maybe the Cosmic Interstate is like the No Zone and exists in perpendicular through all universes).
That is, you must leave your planet and physically go to another planet in another universe, universes that must be perpendicular to Cosmic Interstate due its nature. It is not like a place with doors to each of the universes, it is a place that connects the space of all universes, so it has stars, planets, asteroids and other things, because it is simply the space of all connected universes.
At one point, a sign appeared suggesting the universes were only separated by a few thousand light years in the Interstate
No, that was never the case and I don't understand how anyone had this interpretation. The scene just shows Sonic and his counterparts moving on the Cosmic Interstate and they stopped at a Intersection where a sign says "next exit 148,000 light years". We do not know the position of this place relative to any other place in any universe, it is a reference point from which we cannot draw any conclusions outside "Cosmic Interstate is greater than 148,000 light years" which is very clear with all we know about this place.