... So I think it is with Finn, over the thousand years or so that his family has been cursed, I imagine they have looked into ways to lift the curse, then ways to mitigate it as much as possible. What did they learn? ...
In my opinion, since that circle was so vital to his protection and the protection of others, Finn would have fully understood that it was no ordinary circle and needed a fully qualified wizard to build and activate it ...
I think we may just have to agree to disagree, here.
First, I don't think this info is easy to acquire; not even for those with strong motivations. Generally wizards don't advertise in the yellow pages. Even after you
find a wizard, most of the ones available "for hire" will have found it more profitable to work for a wealthy noble (in past ages) or to pursue their own methods for wealth-generation, e.g. on the stock market, or smuggling high-value small items via Ways, etc (specifics depending on individual wizards' particular strengths & proclivities).
Furthermore, the wizards who
are inclined to do something "because it's the right thing to do" might just find it better to
kill a loup garou than to
help him hide. I expect the average wizard of the White Council would call the Wardens to handle a loup garou!
Also: I don't think the MacFinns have had the kind of lives that foster reliable multi-generational knowledge... likely they've been forced to flee (abandoning everything (including ancestral records!)) more than once.
... Finn would have fully understood that it was no ordinary circle and needed a fully qualified wizard to build and activate it. So why was he messing with someone like Kim? Yeah, she believed in his cause and wouldn't give him away, but I believe it would soon be obvious to him that she had no clue as to how to go about building his circle.
...
it is almost impossible to find a qualified wizard to build one in the first place. So he may have assumed though he was in the phone book under "W" that Harry was a crackpot. But why didn't he at least give him a shot instead of the unqualified Kim?
I don't expect MacFinn had the kind of knowledge capable of evaluating magicians. How would
you evaluate if one mechanic or another is a better choice to rebuild a transmission vs troubleshooting electrical glitches? Or which neurosurgeon is best to deal with an aneurism vs. a tumor? We don't know much about Kim's own strengths & specialties... maybe she was able to present some impressive-to-muggles feats of magic, which most wizards would recognize as fairly simple & low-powered. She may even have impressed
herself.
Why not call upon "W for Wizard" Harry? Better an known ally like Kim -- with at least
some magic -- than entrusting an utterly-unknown "crackpot" with such a critical secret! (YMMV)
... I believe that Kim was as dishonest with him as she was with Harry. Had she survived, I think she would have eventually become a warlock.
You may be right; I don't think the novel is clear on this point.
My own reading is that the foundational "dishonesty" was Kim not being honest with herself: she wasn't "lying" to Harry, she was preserving MacFinn's confidentiality (much as Harry would, for one of his clients). Similarly, she wasn't "lying" to MacFinn, she thought she could get his circle working again. Such overconfidence is pretty common to young people... and of course arrogance is a common feature of wizards!
... Never fully answered, was who knew what he was and who wrecked his circle? Or knew enough about magic to know what it did? The same guys that brought us the belts?
I thought Harry had concluded it was the Hexenwolves, looking for someone to cover their own tracks... or maybe that was WoJ? Or even just a fantheory...
Of course, Denton &Co are even less-likely to have the kind of magical theory to deduce the existence of MacFinn's circle, or to understand what it is/does; not even if they stumbled across it in a search!
The obvious conclusion then would be that yes, the same agency that gave them the belts, also gave them the info they needed to find/ruin MacFinn's circle.
We have a candidate or two... or more...
The "Black Council."
The Demigod of Discord.
Mab, grooming her future WinterKnight.
Some rando White Council wizard, looking to get Dresden killed.
Future!Harry, pulling strings that -- when he traveled back to see "
who was pulling the strings?" --
nobody else was pulling, so he had to
pull them himself, simply to avoid creating a timetravel paradox! They say each of us is our own worst enemy...