This may have been covered before, but Krall/Edison's line about fighting in the Romulan and Xindi wars was interesting. It's almost guaranteed his character wasn't on Enterprise during the Delphic Expanse campaign. Re-watching the show I've seen no signs of other conflicts going on during all that, and of course it's just a retcon thrown in by Beyond, but somehow I like the idea. Warp delta ships, and at least one Intrepid type were patrolling the edge of Sol space after the first Xindi attack (which being vast in 3 dimensions must should have had other ships patrolling as well.) USS Franklin was out there as well, then. It makes sense that the Xindi might have sent other ships in to Earth territory to tackle starfleet ships in order to make it easier for the final incursion. Have any of the ENT books discussed it?