And the key thing everyone overlooks when pointing out all the references to "there have been five Enterprises" not specifying Federation ships is that if they are including pre-Federation ships with that figure, than they're wrong since they're forgetting the ring-ship from TMP.
But that's irrelevant because "there have been five
Enterprises" must always be treated as referring to a specific subcategory of
Enterprises anyway. As of this date, there have been hundreds if not thousands of
Enterprises - seagoing government vessels, seagoing commercial vessels, seagoing private vessels, funnily named automobiles, assorted spacecraft even. Those are
all being implicitly excluded here.
The temporal agents aren't forgetting anything. They are concentrating on a relevant category. Whether one could shoehorn in an
Enterprise that lies outside that category depends on whether we ignore the obvious (that the one thing the five/six being quoted share is that they all are "UFP Starfleet starships") or adhere to it. After all, there's no reason the people of the late 22nd, 23rd and early 24th centuries should suddenly stop naming their interplanetary ferries and hovercars
Enterprise.
But that article is in error. The old
Enterprise in that comic was never shown from the outside - all the pictures are of nuKirk's ship. All we saw was the bridge of nuApril's ship, and neither that panel nor the dialogue refer to the registry number of that ship.
Also, nuApril operated after 2233, so there's no indication that the "joint" past of the universes would have featured a further
Enterprise by any registry, nor any need for the past to have been anything but "perfectly joint".
Timo Saloniemi