There is absolutely no reason to believe that Graendal WILL appear, because as far as we know she was concentrated on Arad Doman and Rand to fulfill Moridin's orders. There is also absolutely no indication in Perrin's or Mat's timeline, which were advanced in TGS, that Graendal played any part there.

As often said, it never happened before that a character, who died in a specific timeline, suddenly appears again in the next book in another timeline before the death. It would likely confuse many readers and is not necessary (BS also told once on his homepage that he doesn't like such flashbacks). You can naturally better advance the plot/timeline and avoid any confusion, if you simply include e.g. an Aran'gar PoV, where she muses about Graendal, her death and how Aran'gar will go one now.

For these reasons it's highly unlikely that Graendal will have another PoV yet, if she died in TGS, like also Sammael, Osan'gar or any other character never got another PoV after their death to give certain informations.