Making Shamiko the butt of the joke aside.... this was a really important chapter for Momo. We got to see that in the past she had actual depression (all the symptoms we gathered by now make it undeniable), we see that she's already met Anri in middle school, which would explain why Anri acted so familiar with Momo being around and we also got to see how Momo's personality changed.
Shamiko changed her life and brought color to it, that much we knew. But it's good to see that everyone gathered around them isnt just there for Shamiko, many of them care about Momo just as much if not more. Momo had a laserfocus on Shamiko for so long that she didn't even notice that she was surrounded by friends who worried about her. Lilith, Mikan, Riko, Ugallu... they are all there for her, even if they show it in very different ways. And Momo finally realized that she wants to protect this town again, not just to preserve Shamiko's smile, but also to protect her own happiness she built here. I think that's beautiful.
Also good to know that the theories were correct. Momo got those scars from fighting another magical girl, because only ether can put permanent scars on ether bodies. The way Momo tried to warn Shamiko that she will see some bad things, but that she is still alive and well is certainly implying it. Some overpowered magical girl on the level of Sakura is certainly dangerous. I wonder what her motive is? If Komomo managed to repel her she must probably have spared her, rather than having lost. Could she be connected to the Dark Office getting destroyed?
This arc is already the most interesting.