In Xenoblade Chronicles 2, it revealed some face value evidence that the "Phase Transition event that destroyed and recreated the universe" wasn't just Universal but Multiversal in scale. Given that both XB1 and XB2 had the exact same "Original Universe" that was destroyed by Professor Klaus, but both universes perceived its own universe as being the universe that was destroyed and recreated. There used to be counterarguments claiming, "Isn't this just a range feat and not an AP feat because XB2 simply said that the population and half Klaus' body was simply teleported?" It never retconned XB1's claim the universe was destroyed or that there was Universe birthing, it simply added context and elaborated saying it did more than just that. Anyone who has played XB3 on the other hand will easily tell you that the original feats absolute lowest interpretation would be 2-C; since the entire plot is that both universes were created by Zanza/Klaus and desired to be merged back into one universe.
But as for the 2-B to 2-A stuff, yeah, the Architect went over the existence of "An Endless number of universes existing side by side". People were knit picky about Endless being Infinite a long time ago, but we recently accepted it as a possible synonym with the word Infinite. But at least 2-B, possibly 2-A was something accepted based on that. Also, one of the guidebooks from Xenoblade Chronicles X also took a step further and mentioned some device that created an "Endless number of Universes" as well. Also, it's important to note that all Xeno games; not just Xenoblade but Xenogears and Xenosaga have the exact same "Birth of the Universe" origin story where it is mentioned that an extraordinary genius scientist who found something called the Zohar/Conduit/Gate from Africa and used to destroy and recreate the universe; with both Xenosaga games and XB2 taking it a step further saying it wasn't just the universe but many universes and possibly the entire multiverse was created. Most of the Tier 1 statements also comes from Xenosaga, particularly Albedo having the power to "Shove the whole dimension into a high order domain". Also, we might get even more details in the upcoming DLC wave coming near the end of the year for XB3.