I have found the last piece of the puzzle for my personal head canon for Proven Guilty.  This shouldn't be confused with the truth, whatever that is. I still have no idea of who fixed LC.

There appear to be two murder plots running concurrently in the text. There is the obvious one.  The Merlin being manipulated into trying to kill Harry once again.  This is probably the WC traitor (Peabody) stirring the pot. Magic ink and all that.

Then there is the  second plot. The one by the Denarian's, possibly/probably  in concert with the Black Council. This one is trying to either get Harry to pick up the coin or to kill him if he uses LC, by having it blow up in his face.

This second plot is inferred rather than explicit. This is tenuous but the reasoning is thus. Lash shows up two times in the book, unless I'm forgetting one. She appears just before the crash and she appears just before first use. She is the only one who could have blocked Harry or Bob from seeing the flaw in LC. If Nicodemus is to be believed she could have controlled Harry and told Bob to not see it.  Harry never would have known.  Her active intervention let Uriel put his thumb on the scale.

Why didn't Rashid just tell Harry what Molly had done.  They had to empty the basement so someone could get in and fix Little Chicago.  In addition Mab had to show Harry the attack on Arctis Tor so Harry could answer the first question that Eb asked. Why didn't Mab declare war on the Red's?  Thus answering the question, why did Mab have Molly brought to  Arctis Tor?

For my personal fan service and head canon this is good enough.  It ties up most of the loose ends.

Assuming true love, who wears the latex? Or does Lara bring in a third party, ala Justine?

https://www.penguinrandomhouse.com/books/611814/heroic-hearts-by-edited-by-jim-butcher-and-kerrie-l-hughes/#

Was Malcolm a Scion of an Angel? Eb appears to have seen him under the sight.

"She met your father. A man. A mortal, without powers, without influence, without resources. But a man with a good soul, _{like few I have ever seen}. I believe that she fell in love with him.

That is a weird description, like something you would say about a saint.  Malcolm is also the only character that speaks to Harry from the afterlife.

I'm sitting at my desk drinking a really good Small Batch Bourbon and listening to some of my favorite music and had a melancholy thought. Was Mab's order to Harry a foreshadowing?  Will Harry have to kill Molly?  Worse yet, if true, who will Molly kill before Harry can stop her? I can't really say there is any one thing that is the genesis of this thought, but it does follow the general theme that Butcher has always presented.  How can I torture Harry?

Since I'm shipping Harry and Mab, in my minds eye I see Harry holding a dying Mab in his arms as the stars go black in the sky.

This can't be a coincidence, can it?

Nicodemus studied me for a moment before smiling. "Apocalypse is a frame of mind," he said then. "A belief. A surrender to inevitability. It is despair for the future. It is the death of hope."

“Apocalypse isn’t an event,” Nemesis murmured. “It is a frame of mind.” I probably would have staggered anyway, but the phrase hit hard. “This was less a plan than . . . an act of faith, I suppose you would say,” the Outsider continued through Justine’s lips. “Faith?” I asked. “In what is coming,” the Walker said. “The unraveling of all things into darkness and silence.” “Empty Night,” I breathed.

Butcher, Jim. Battle Ground (Dresden Files) (p. 361). Penguin Publishing Group. Kindle Edition. 

Here we have a secret that a lot of people know about Harry.  The question is why won't they tell him, isn't it? In fiction that can only mean one thing. Whatever is going to happen will be interfered with if Harry finds out early. It reeks of time travel.  

Another interesting idea(to me) is the castle.  Why introduce it?  And why place it at Harry former home? Was Jim laying foundations? The Marcone's vault was the key to opening a portal into Hades domain. Is the Castle the key to opening a portal somewhere else?

What kept Mab from marrying Lara? Think about this one. Is Lara Mab's  mortal child?

“Not possible,” Mab said. “If it was work I could do myself, I would.” Which . . . I believed, actually. “Why not?” “Certain aspects of my power have to do with choices I made when I was mortal,” she said. “There would be . . . compatibility issues. This is part of the task the Knight was designed for.”

Butcher, Jim. Battle Ground (Dresden Files) (p. 395). Penguin Publishing Group. Kindle Edition.

Did Mab have a child with Papa Raith?  Jim reuses ideas and Margaret did leave Thomas to his own devices. That would be one hell of a compatibility issue.

I got a ton.

Was just thinking how odd it is after reading Battle Ground, that Margaret was in DC right before she died. You know less than five blocks away from the Library Of Congress.