master spark varies on what it is exactly, but if you mean the strongest one then... no it's definitely the kind of thing that goes well above mountain there. the 'normal' master spark is different, but what she fired in the manga was final (master) spark, which is the attack at max power. also noting is that it's something powered by a furnace that burns down mountains, not that the beam itself takes out mountains. considering it's just a concentrated beam, makes a lot more sense that it's well above that.
touhou isn't really a slouch on power with some spell cards able to be debated as to being planet busters, another character that makes actual suns, another one does black holes, etc. i wouldn't argue this being light speed because it really doesn't show or imply that enough for me to agree with that, but power isn't something i'd question.
there's also a pretty big difference than a concentrated beam not much bigger if at all from miracleman and a giant building. one of them requires taking the complete and entire brunt of an attack. the other requires you to really just needing to be able to go through the part of the building falling on you.
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The King Wang.
Listen up Urinal Cake. I already have something that tells me if I'm too drunk when I pee on it: My friends. - Colbert.