>>94231657I mean, in groups Shiori does tend to be the most even-keeled and cool-headed, not too different from Kronii. I'd imagine that's how she acts in a professional setting (i.e. during auditions) and thus Cover possibly underestimated how manic she gets when she's solo.
All that said, I don't think Shiori was supposed to be a wet blanket Daria type like you're describing. The character is meant to be an evil librarian, inquisitive and creepy. I think she fulfills that pretty well in her own way, although I sympathize that she's a little more dorky than I'd imagine for the pitch.