I dont think thats accurate.
To my recollection, he uses magical inks to influence the White Council in general and the Senior Council in particular; his position as a senior clerk allowed him to get people to sign shit.
Harry's distaste for documents and signing shit, as well as his general distance from Edinburgh kept him safe.
But we are never told exactly how he installed his controls in people.
Ink is probably the safe bet, but its never stated.
The ink was the proof he was actually doing it, just having all the ingredients in it that it did was considered damning evidence by everyone in the room when it was revealed.
That entire thing suggests that they needed external help to go in and clear everything out
Not that it resolved itself once it was exposed
This one I was wrong about, I think I was mixing up the part where Harry mentioned that the forced pause could only delay the Wardens for so long just prior to Peabody's escape attempt.
A wizard traitor looking to backstab his co-conspirators would write out the names, look at them with the Sight to burn it into memory, and then burn the physical copy. Which makes a completely secure backup.
And thats just the first option I could think of; there's probably more.
Wizards really don't like screwing around with the Sight. The guys who do that tend to go nuts. This particular use would be fine, but there's a cultural inertia to it.
If the conceit is that all we got from a larger data set was names there's potentially more to work with.
The general point is not to be foolproof, but to be plausible and point somewhere other than admitting what we're doing.
Yog's original plan called for sharing the list on the basis that we figured it out by looking at Tina's bindings.
The crown is a perfect effect that allows us to follow associative links to answer any question related to a foci. The implication of our claim here with the names would be that we took one look at someone's magic, followed it back to them, followed that to their patron, then forced our way down stream from whatever the hell their Outsider patron is to pick out other traitors. Who conveniently we have names for and not just aura prints, voices, or faces.
A diviner would have to do a lot of time consuming shit to start this and then follow up with mundane investigation to close the deal. We're not using mortal magic, we're basically telling them we have an unconventional thaumaturgical effect that can do third order searches past multiple layers of Outsider bullshit and whatever the warlocks are doing to defend themselves.
Which I contend it basically telling them about the crown because the only thing being obscured is the degree to which it is good at piercing defenses. If they put any thought into this at all the conclusions are either that we lied about when we noticed the problem or something like the above ability exists.
In reality both are true, but with how haphazard this is going to be I don't think the scale will lean towards this being a plot on our end.
We aren't Lara or the Gatekeeper. The former has several possible vectors and enough lead time to make it hard to guess more than the generalities of her sources. The latter is a senior council member and trusted authority.
I don't think the way Dresden treats them is how the Council will treat us, and if they did it seems overly optimistic to conclude that they won't make basic inferences about what we did.
The tech explanation is unusual, but it's far less crazy sounding than the alternative. It plays to their biases and areas of ignorance instead of putting basic puzzle pieces from a subject they understand directly in their hands.
