It strikes me that there might eventually be an issue with Butters and Bob playing Batman, and that's the Council.

Remember, Luccio told Harry that they knew about Bob, as a former assistant-spirit to Kemmler.  She also said that the Council had a 'destroy on site' order out for Bob, because he was too dangerous to be allowed to run loose, and in fact that he had been destroyed.  In fact, of course, Justin had taken the skull from Kemmler's base and Harry had inherited him.

But now Butters is out there using Bob to energize various magical weapons and tools, and using them relatively openly.  If the Council notices that Butters is suddenly wielding devices using way more magical energy than he should be able to manifest, someone might get curious as to how the former medical examiner is suddenly tapped into so much power, and if they took a closer look and realized how he was doing it, then suddenly Harry and Butters and the Chicago Alliance have Trouble with a capitol T right here Lake Michigan City.

I wonder if anybody's thought about that risk...

I think you are underestimating how much Sarissa is part of the conspiracy to kill Maeve and make Sarissa the Winter Lady.  The whole book is written essentially under one context and Harry (and us) take that to be the truth.  But go back to events and remember that she is Mab's daughter.

Let's roll it back to the very start of the book.  Sarissa never says, "Mom" to Mab.  When she talks about her relationship with Mab, she doesn't outright lie but does not tell the truth.  Then she shows up at Molly's place.  I want to remind you at this point in the book Harry thinks she is a young, Mortal woman.  Under 30, maybe under 25.  The Redcap would know that she is Mab's daughter.  He likely pre-dates Mab.  So, do you think he is really going to KILL Mab's daughter?  How would that go for him?  More likely she let her self be captured by him and sent to Harry.  I suspect all her hiding is not her fear of Harry, but instead fear that he will recognize her as Maeve's twin.  The next event is the "team" crossing the circle at the top of the island.  There is no way to force her into the circle and make her stay.  She went into the circle willingly.  The plan was to have Maeve killed and pop the Winter Lady's Mantle into Sarissa.  Mab knew it AND so did Sarissa.  Look at her argument with Maeve.  She clearly knew that Maeve was nFected.  She compared Maeve to Lea and how Mab could cure Maeve. 

We tend to assume that the people working against Harry and the good guys are Nemesis-infected or Nemesis-influenced, and obviously some of them, like Maeve, are so.  But it's not clear that Aurora, for example, was suffering from exactly the same thing Maeve was.  There was no indication that Aurora could actually lie by commission, for ex.

Likewise, there are people working for the other side who almost surely are doing so of their own free wills (or as close as the supernaturals have in some cases).  They may or may not be allies, but they probably do work together sometimes (and maybe against each other at other times).  I strongly doubt Cowl is Nemfected, for ex.

Regarding Sarissa, see nambkas' comments above.  Sarissa looks to be far more than what Harrry took her to be in Cold Days.  But just as a speculation, suppose Sarissa is actually Circle, or working for/with them (presumably even unknown to her mother).

That might seem improbable, but it might also explain a few things.  For ex, Maeve hated being Winter Lady, apparently.  She apparently also hated Sarissa, though that may have been jealousy over her relationship with Mab, and/or her personal freedom.

But how did Maeve end up as Winter Lady in the first place?  Why Maeve and not Sarissa?  From Mab's POV, Sarissa looks like the better candidate.  More self-disciplined, more serious.  I would think that Mab would have preferred Sarissa to be the Winter Lady.  Yet somehow Maeve ended up with that 'honor'.

But if Sarissa was with the bad guys, even back then, of her own free will, it might make sense to let Maeve have the title and the power, since that way Sarissa retains her freedom of action and her semi-immortality.  She can always become Winter Lady later, if need be something can be arranged to happen to Maeve...

If Maeve was somehow forced into taking the Winter Lady status, that might also have contributed to her hated for her sister.

Just speculating...