I am sorry but as for the page 34, the "思い叶わなかった時" in the last lines of Patchouli, might simply refers to the wish of Shanghai.
So I think what Patchouli suggests here, is that when Patchouli has successfully confessed to Alice, which should make Alice unavailable to Shanghai and totally break Shanghai's wish, she will try to make Marisa take responsibility and marry Shanghai as some compensation (becasue Marisa promised she will help Shanghai become human and win Alice over)
Besides, this one is somehow followed by two later ones along the story line, which make me further prefer my comprehension fo page 34
There always exisits ambiguity in colloquial conversations(especially japanese) in doujinshis. So I think the translation could have multiple options maybe.
...Ok I'm starting to feel better about the pairing. This gives Shanghai character, though unrelatedly I feel bad Hourai gets left out. Go Marisa! Find the spell!
@Bigbigfool: I was wondering what was going on since after that last one showed it has a over arching story so that page made me confused still good work from Yohane as always.