She is sitting in the library, studying. It's her most common pastime, by hours; spending time with her sister is more enjoyable but Jaromira prefers to socialize more broadly and Katarzyna would only get in the way. This is better on net; the two of them share a room, so it isn't as though her sister's time is entirely hogged by the other girls who call this boarding school "home." Or at least "prison." Katarzyna doesn't mind it, though; the school library is excellent, and basic manners and care for the books has endeared her to the librarian to a sufficient degree to lubricate the interlibrary loans process when there's something she wants to read that they don't have.
The next day, Katarzyna shows up to magical girl club with her fancy new stardarters.
In the brief window before Natalie starts her presentation, Gabrielle congratulates her on them and Brooklyn asks if she has any plans to actually shoot at swarms.
"Not in general, but it turns out my magic sense is actually the passive form of general metamancy and I should at least figure out if I can do anything to them that way."
They are called down from their flying interlude to listen to Natalie and take shots at targets while they're doing so. Natalie discusses Britain's history of organized and militarized magical girls due to their island status and naval incentives, and inland Prussia's ability to deploy magical girls against non-swarm targets due to the low incidence of kaiju.
After which Katarzyna screws her courage to the sticking-place and announces that apparently she has metamagic, she and Isabella ran into each other over the course of the week and discovered that Katarzyna can maintain, nullify or mimic Isabella's stopping but at a weaker magnitude, does anyone want to try anything with that.
Can she copy Faith's power to make a giant peanut even gianter, or does it not stack like that?
Yes, that's what she was wondering--can she switch to copying Isabella's power fast enough to stop the peanut from shrinking?
"I switched to copying Isabella's power to keep it from shrinking, mostly to see if I could. I'm sorry, I probably should have said I was going to beforehand."
"I've been wondering if I could do anything cool and synergistic with copies of different powers but I'm not sure how 'stopping' and 'size changing' would cash out together."