Regarding the polyamory thing, other than the fact that I was hoping for a MJP triad from the beginning, I also believe that there is a good chance that Panoramia won't have much of a problem with being non-exclusive.
Other people have already established that there is little reason for the popular gods of the Empire to be against homosexuality. So there's nothing saying that it might very well be something that gets more or less openly talked about even in high society. That said, Taal & Rhya are very likely in favor of marriages with copulation and conception, Sigmar looks fondly on alliance building among humans, population increases and keeping dynasties alive, and fertility cults are about, well, fertility. On top of that at least among nobility marriage is about alliance and inheritance, and nobility are the ones that usually make up the more enshrined laws and social norms. So while I don't think there's anything in the way of people in the Empire living in homosexual households, I still think that marriage as an institution would be a heterosexual thing predominantly everywhere where people have valuable property and that many of the Empire's homosexuals would be pressured into marriages and continuing the bloodline without that necessitating that anyone expects them to break off their prior relationships.
Yes, that might lead to the Empire considering homosexual relationships less "serious", similar to many ancient European societies. Which is unfortunate. But all in all, I don't think that the idea of non-exclusivity would be in any way foreign to Panoramia and that, as long as it doesn't happen in the NRE phase she wouldn't necessarily even feel hurt or wary.
Personally I would prefer a Δ relationship over a V anyway, but I expect those to be more rare (though not unheard of in gossip) in the Empire.
Anyway, all this is just my own speculation and I'm not going to insist on trying to achieve it. For now Mathilde is far too inexperienced to be looking for more when she hasn't even figured out how the two person relationship actually works in practice.
Even though it doesn't speak to me, it seems like a relatively good fit.
Whichever ends up working best for future writing.
And I assume that they might have done handholding and casual touching of hair and clothing, but nothing off screen beyond that yet?
There's an apparatus of support staff under the Dean that take care of that sort of thing.
How good of a childhood does the Grey College actually provide? I'm imagining something a bit stricter (and with more punishment beatings) than an old-timey boarding school. Maybe better (though more specific) education and less luxuries. But not quite movie medieval orphanage or convent and definitely not Marienburg orphanage.
As to how, there is no how, anymore than there's a how to how the AV transforms into the Winds on contact with concentrations of them. I expect it to transform into whatever flavour of magical energy it touches. Touch it to a concentration of Ranald energy, and I expect it to transform into more of Ranald. Touch it to a concentration of Dammerlichter energy,
That is not how it works. When exposed to one Wind or to Dhar, it becomes eight Winds. Why would it react differently to other stuff? But sure, after the expedition is over I personally won't stand in the way of dipping our Coin in it or whatever.