More thoughts about the Riona interaction: I was thinking about how I'd handle this in Sabrina's shoes, though I'm not sure that's how Sabrina can handle it, just because of who she is; I was actually going to write up a quasi-omake with the reaction of 'Brinabrain Contributor 612' to the whole thing but couldn't make it work right.
In the immediate situation, I'd brush over or ignore Riona's rudeness (it's possible I wouldn't even notice it, honestly; social obliviousness is like my 7th name), or at the most acknowledge it briefly with something like "I don't know you from magical space Jesus, that's a rather personal question".
Then a short answer about the non-infosec-requiring information, basically like the frankenvote I put up earlier. Something that didn't come across in that vote, but when trying to can down on my (and I think Sabrina's) tendency to go for longer, flowing sentences, I think overcorrecting to short, terse syntax would be the result;
"The grief control was what I wished for;
Kyubey said my soul was strange;
I don't know why;
I was hoping you might know more.
I do have a few ideas;
I don't want to speak about them in public;
I have information security measures I can deploy;
can we do this in a more private place?
[telepathy: I know certain things about Magical Girl life that Mami has chosen not to know.]
I would like to work with you in the future;
I'm curious why you're here;
how did you hear of me?
[when in a privacy sphere, with Mami outside for safety]
Before I start, can I ask you a few questions;
what do you think of Kyubey;
what do you know about Witches?"
It would be as much keeping things in order for myself as possible, but if Riona wants to get to the point, that's as to the point as I can think of. I wouldn't be able to help making so many of my statements questions, but for Sabrina, things like "Can we do this in a more private place?" would be better phrased as statements, "Let's do this somewhere more private."
Longer term, I'd be keeping caution. It's interesting how fast we went from "Riona is a possible threat who could insta-gank us and we want soul gem protections out our ass just in case" to "how do we avoid offending her so we can be friends/fuck it let's offend her she has no right to be this rude". We still know almost as jack-shit about her as we started, beyond a little more insight as to the brand of rude she is, and the fact that she doesn't seem like she wants to insta-kill us right now. People have layers; people are multitudes; it's still possible that Riona is a hostile. Says my paranoia, if nothing else, and caution is still the watchword of the day.
We want her as an ally; until we know we can trust her we should still be keeping at least as much an eye on her as we now keep on Oriko, not house-arrest-wise, but in the sense that I feel like particularly up until the Long Conversation 'yesterday', there is or was still some need to keep an eye on what she's doing, if not for our own sense of security, than for others. Riona, like Oriko, could do a lot of damage; we hope that she won't, but we don't even know as much about her as we do many other folks in order for me, at least, to feel secure making that bet.
... eh, that's all I've got for a moment, I just suddenly felt the need to articulate all that.