Demandred doesn't appear in ToM, at least not as himself. The fact that Murandy with its new king is the only nation (other than the Seanchan) not to answer Egwene's call to join her outside Tar Valon was rather interesting though....

As far as the Black Tower goes, there's a couple chapters with information letting us know more about what's going on there, primarily through the Tower Embassy's PoV, but no major action.