I also have heavy doubt about it based on other statements there. I was originally going to write them to OP then let staff decide. I'd like to hear yours here too, though. (I might just not make the thread at all based on it)
Sphinx's first Al Shario was aiming to where Cecilus, Al, and Arakiya were. Her goal was Arakiya's death, and thus the destruction of Vollachia by way of Muspel ceasing to be.
Echidna's Al Shario and Alter's Al Shario(s) didn't destroy Lugunica.
Priscilla actually says in arc 8 chapter 70 that Sphinx would need numerous Sphinxes casting Al Shario to destroy Vollachia, which clued her in to the weakness of the clones sharing mana reserves.
あとはプリシラを絶望させるため、ヴォラキア帝国を滅ぼしてしまえばいい。そのためには無制限にスピンクスを作り出し、地上に流星群を落とせばいいのだ。
Would his base really scale?
Yeah. Clind is not hitting harder than Vague, let alone Reinhard.
Didn't he use multiple attacks?
Nah.
Didn't Alter fell after Reinhard threw Al Shario to him? He even tried to stop the star with his breath.
Reinhard kicked it at him, he triggered its explosion with his breath, and was left brutally injured. But that's the weakest Alter ever was, he got way stronger after downloading Al's 130k loops and fighting Wilhelm.
Alter's breath is canonically below Al Shario, no?
I said "breath", but technically he just used magic inside his own mouth to create an explosion, which Al Quartet was used to counter. When it was just his uncharged dragonbreath, Clind could slice through it bare-handed.
And while Al Shario is described as destruction beyond dragonbreath, it's hard to say if Volcanica (by extension, Alter) is included, particularly their fully charged breath. Alter's fully-charged breath was equal to Al Quintet, after all.