The bigger issue is that most people have a very big misunderstanding on HOW aurum works. There have been multiple cases where I've been aurum tested on Sermi (RIP) and they either emote it being a pinprick. Rarely have I ever seen it done to the degree that it is SUPPOSED to be. The only time was actually a rather entertaining interaction in the Holy See where she was aurum tested x6 times and almost passed out from blood loss.
I definitely agree on your point with that extra yap. Obviously I started in Haense and my only introduction to magic was because I had people in those circles. Otherwise - I would have been blissfully unaware of a lot of it for a long time. The only thing that touched lore there, when I was a pink tag, was some guy doing meme-quality 40k RP.
It is definitely an uphill battle. I think ultimately we're stymied with the fact that bad faith actors will always be bad faith. My mindset with this is to try and limit the opportunities they have for destruction on other rp. It really sucks to build up a plotline only for something to be skewed awry by metagaming / powergaming / etc, etc.
I think most of it goes back to 'winning', and the company you keep. As much as I loved my interactions with you, I had a LOT of issues with the rest of the Canon church that made me distance myself from roleplaying around that group. Unfortunately in many such cases, that leads to just creating an echo box that helps no-one. I've been very careful to avoid that - but I have seen it in other communities.
Long-term, I think the best solution is definitely to offer Corc some form of progression. Have it start subtle, and then grow more agitated to testing methods when it feels more thematically appropriate. I.E - maybe they don't react to aurum or salt nearly as much until they progress into the next tier of FA/MA/CA/Whatever happens with vampires.
It's unfortunate that in most cases, while people do present as good faith; you have to protect yourself from the bad faith actors. Even if it's only in 1 in 20, the impact an individual can have in some cases can ruin months of storyline with very little way to interact with it otherwise.
To borrow your term and yap a bit more, another big issue is that so many encounters just end in death. Rarely have I seen instances of characters being given legitimate chances to grow. It's just 'grr darkspawn kill them!'. I recall when @ibleesiantaught some of the Haensers that you can, in fact, push them to give information that might lead you to bigger targets instead of just stabbing them to death. Many people treated it like it was some grand revelation.
Lots of points to consider on all sides, for sure. I hope it doesn't read as me rejecting your concerns outright, I've always appreciated your RP and willingness to talk on the matter!