I feel like you're missing a crucial detail here. That is the full power of the Moon Cell being channeled into an attack program used by Hakuno. All of that energy is still limited to what Hakuno can do, and what attack programs can be. This is no different from Rin using the magical energy of the Jewel Sword, which is theoretically endless, but being restricted by her own limits. Even Servants have limits like that, just like how giving a several Holy Grails to an average Servant with an average Noble Phantasm is not gonna make them stronger than fucking Ea or something. Also, think logically about this, that was Altera on her 1st stage since she's 16 meters tall, and we know that 3rd stage Sefar (64 meters) could be injured by the likes of Vasavi Shakti. It'd make no sense for the Moon Cell's full power to be weaker than Vasavi Shakti, since that is something that the Moon Cell can reproduce by itself, as evidence by it fucking summoning Karna. And it'd make no sense for 1st...