I would very much like Graendal to be alive, because I'm most disappointed with her "last round", but I think alas you're probably wrong.

This book made abundantly clear that there is only one Forsaken who counts, and it's Moridin. The only reward Moridin wants from Shai'tan is for him to destroy everything, Moridin included.

Moridin knows he's just a tool, a mean to an end, and unlike the others he embraces this, he is a most willing tool He knows he is Nae'blis only until Shai'tan destroys everything. If they fail, it will happen in a next turning.

Moridin needed Graendal, and she served him all right. Normally, Graendal would have fled Arad Doman. Moridin gave her a strong motive to stay: she would be his second, she would be rewarded. He did even worse, he ordered her to get involved with Rand directly. Remember the Sha'rah scene, what happens to those who go for the Fisher piece. All the Forsaken who went against Rand have died, incl. Ishamael himself. None of them has survived a confrontation. Moridin knows this, and he knows what killing women does to Lews Therin. He knows all too well.

Shai'tan expanded Semirhage by letting her bring Rand to the right state of mind and than betrayed her by letting him use the True Power; and Moridin similarly betrayed and expanded Graendal. What Moridin wanted Graendal to do, she unwittingly accomplished by making herself Rand's target, by making Rand kill her. Pain of heart, anguish - she brought to Rand by how she died. Graendal was fooled by the promises of rewards (and Moridin's scene with Rand made clear Moridin lied to Graendal about rewards) and remained in Arad Doman until Rand found her, just as Moridin expected she would. He played on her greed to gain some loyalty, and he fooled her.

Moridin's endgame is coming. If Forsaken need to be sacrificed to accomplish goals, they will be. Shai'tan doesn't have millions of Aes Sedai and a high-tech civilization to destroy anymore. He has a world already on the brink of destruction facing him.

So, it's a nice theory, and as I love Graendal and I'm disappointed by the barely existant part she played in this book I would love it to be true, but I don't think you're right about her surviving.

Brandon made a series of small continuity mistakes in her story line, and I'm pretty sure the back story of her palace is simply one of those, just like having her near a window contemplating nature outside in the prologue was a little continuity mistake.

But you may be right that she survived, and there's any number of ways she could have done it (RJ shaped the OP as the plot needed). But I don't think the rest of the theory is right. It's pretty obvious, I think, that Moridin meant to sacrifice Graendal. If she survived, she'll most likely return among Moridin's enemies, like Aran'gar, like Demandred and Mesaana. They're all too stupid to understand they must turn on Shai'tan, but it should be only a matter of time before they ally against Moridin, if only because they realise now where following his orders have lead Osan'gar, Semirhage and Graendal. But they may be too stupid to actually ally.