To clear up the page 12 sound effects:
The first one isn't tsutsun, it's fufun (フフン), kinda like a boasting smirk. Similarly, the one after that isn't gantz (ガンツ), it's gan(nnn) (ガンッ), that generally disappointed realization as her idea is rejected. Sound effects/onomatopoeia can be a pain in the ass to translate at times when you're not familiar with all their forms.