I remember a scene from the third X-Men movie; The Last Stand, the one that totally botched the Dark Phoenix storyline, where Magneto sends a bunch of his recruits into battle, but holds his most powerful ones back and says of the first group, "They're cannon fodder." I get the feeling there is something similar going on with the Black Council or Circle.
There are actually a surprising number of people and not people who know something is going on, that something big is about to happen and for various reasons see it as an opportunity to gain power for themselves. Only a few are really clued in and they don't have any problem with using and sacrificing people they pretend to bring in to the conspiracy. So for example, it's possible that Cowl was behind some of the planning that went into the assault on Demonreach island in "Cold Days," but he sure as hell didn't make himself a potential target by riding on any of the barges with the practitioners who were attempting the ritual to bring down the island prison's defences. In "White Night" Madrigal Raith thought he was joining the Circle, but even Vitto Malvora thought of him as a fool who could be sacrificed as the need allowed. Vitto was given power by an Outsider, but I would bet that Cowl thought of him as nothing more than a tool that could be sacrificed when the need arose, as it did.
We know there was a plan of some sort discussed by Margaret LeFay, Duchess Arianna of the Red Court and Lord Raith of the White Court. We don't know, but suspect that plan is at the heart of the Black Council / Circle. The first two people named are dead and the third might as well be dead, though I suppose it is technically possible for Lord Raith to make a comeback. Justin DuMorne had been a sometime ally to Margaret LeFay; presumably when she was full red light saber, so he may have known about the plan and he may or may not have been in direct contact with the Outsider HWWB. Harry believes that Justin called up HWWB, but Harry isn't a 100% reliable narrator. Margaret tried to get Ebenezer McCoy to join this conspiracy, but he refused. At least, that's what he told Harry. Finally, it's theoretically possible that Lara Raith may have learned something of her father's role in this plan, if she didn't turn him into a potato before she thought about questioning him for useful information. However, Lord Raith may have been too dangerous to do anything less than give him the equivalent of a lobotomy when Lara pacified him, so she may still be in the dark.
It seems to me that one day, when Harry gets more clues about what's going on and becomes a little bit inquisitive, he's going to have a conversation with Ebenezer and see if the old wizard can tell Harry about what Margaret's plan was about, assuming it has anything to do with the Black Council / Circle. Of course, Ebenezer could die before Harry ever thinks of asking his grandfather about that scheme. In fact, I think it's more likely Ebenezer would bring the subject up first, and might do so if he was dying and Harry was there.