In the Kanzentan, it explains that base roshi used a super kamehameha to destroy the moon, and used normal kamehameha wave to try putting out the flames on Mt. Fryingpan. You don't understand that Roshi wasn't putting his all into his kamehameha wave against the flames, but used max power form to increase his control, but still ended up accidentally destroying the whole mountain.
The Daizenshuu was translated into english from the original japanese scripts, and you can actually look up most of them on google. The Kanzentai is also one of those DBZ encyclopedia's, but it solely describes techniques use in the series. It described Tien's light speed fist, as "a technique where the user builds up ki in their muscles and shoots it forward so the arms follow, making the fist move as fast as ki which can be manipulated to move faster than light!".
How is the DBZ anime non-cannon? The DBZ anime was made the way Akira Toriyama wanted it to be. The only thing that was non-cannon was the english dub, which was still correct for most things besides about three translation errors. If Akira Toriyama didn't want to make Broly, he wouldn't have, but he in fact said in Otaku magazine that Broly was one of his favorite characters. Since he made him, and wrote the drafts for the Broly movie, Broly is at least as cannon as Garlic Jr.
So what if it was a chain reaction? If he would have destroyed the multiverse by screaming, HE WOULD HAVE DESTROYED THE MULTIVERSE BY SCREAMING. Why not just say that Galactus fighting with Infinity and Eternity wouldn't have destroyed the multiverse because it would have collapsed it and caused a chain reaction? Why not say that Superman chasing Supergirl wouldn't have destroyed the universe, because it would have only done so as a chain reaction? That's completely undermining and blowing off the power of characters just because of your preference.
Whiss stated that Bills can destroy quadrants just by getting angry. THAT IS 1/4TH OF THE DBZ UNIVERSE. The universe in DBZ is explained in the Daizenshuu as divided into four quadrants that are equivalent to about 100 billion galaxies each. Bills is able to destroy a quadrant, about 100 billion galaxies, JUST by getting mad. Bills said Whiss created the 7th universe and the god tree, that spawns kai's. While creation has nothing to do with the destruction aspect of power, all of the Buu's were claimed to be universal threats, and Bills one-shotted Buu for eating all the pudding. Whiss knocked Bills out for three years with A NECK CHOP(Dragon ball Nam reference, lol).
Also, it wasn't a "universal scream", Old Kai said that Buu screaming would destroy "all of creation", not just the universe. While I admit that the feat of surviving a universal explosion and creating a new, similar universe IS very respectable, it simply isn't as great as nearly destroying the multiverse with a scream. Goku and Grand Kai said that fat Janemba's pure power was able to destroy the whole universe, and SSJ3 Goku curbstomped him until he went super. Also, Goku can take more punishment than he can dish out, as seen when he shot a full power kamehameha around king kai's planet, and flicked it away without getting hurt by it at all.
One last thing. How is creating a universe a display of power? Iirc, there were two pokemon who created the universe, but their battle didn't even destroy a town because their blasts were so weak. They were probably weaker than Raquaza. Just creating a universe doesn't mean you're unstoppable, considering the fact that the supposed god of pokemon who created the two that made the universe, nearly got killed by an asteroid and got hurt by Pikachu...
So no, while Alien X is admittedly powerful, he falls short of DBZ.