Well, I think we're going to see some sort of convergence between After the Fall and Season 8, which is why Joss is keeping mum about what (if anything) the team knows about Angel and Spike right now.
First of all, the presence of time slips in both series seems to me like a huge indication not only that something similar is going on in both series but also that some syncing up of the two different timelines is possible. I'm not saying it's inevitable, but I think it's possible. I even think it is highly likely, as it would seem sort of sloppy to me if both stories involved time slips but had no common factor driving or enabling those time slips. Joss is not normally known to be sloppy, especially not when he's dealing with large, overarching plot elements like these.
Second, I'm seeing a lot of connections to Fray within those time slips -- and again, I'm seeing that in both series. During one slip, Spike was seen holding the scythe in Fray's timeline. Similarly, a much aged Angel was seen driving a car in that timeline. Obviously, Buffy went to Fray's time for the duration of an arc. I'm not sure how Fray is going to play into all of this and I've never read the Fray comics, but I'm getting the feeling that both our slayer army might and our HelL-A apocalypse play into the whole banishment of magic from this realm that sets Fray up as the kind of half chosen one. At any rate, Fray is yet another of the things that season 8 and After the Fall seem to have in common.
Finally, we know from Beta George's attempt to seek help from the world beyond LA that HelL-A exists in an alternate dimension separate from the "normal" world of the Buffyverse. Similarly, we know from the fact that -- despite Willow's warnings -- Fray's world and timeline exist even after the events of the Time of Your Life arc, that they, too, may exist in an alternate dimension separate from the Buffyverse. This existence of multiple separate, yet interrelated dimensions and timelines suggest to me the possibility that Buffy and co. may know nothing of what goes on in Hell-A until or unless a time slip or other convergence occurs.
So, in a nutshell: I think the two series are currently operating in different timelines in different dimensions, so I don't think she knows yet. Given the instability of these multiple timelines and dimensions and their tendency toward convergence in Fray's timeline and dimension, I think Buffy's going to find out. I think both series are headed toward a conclusion (or, at least, a climax) involving Fray, and I think that is when the Hell-A arc (as well as Spike's resurrection) will be revealed to Buffy. Wherever Joss is taking us, I think there are larger things at work here than a simple revelation of Spike's resurrection.