Saying "Well, you can't prove your case" does not make a person right. As with all science, the burden of proof lies upon the person putting a new theory forward.

As I stated above, lack of a direct quote stating that "Graendal is toast" does not mean that she isn't. As with my last post, Kerb could just have easily been a lead planted by Moridin as a lead planted by Graendal; in fact, Moridin has means and motive, while Graendal was clearly unprepared for the attack. The only explanations for her survival rely on suppositions which have no evidence in the books. Whereas explanations for Kerb's compulsion and behaviour are a dime a dozen.

A few quick possibilities off the top of my head:

1 - Graendal DID intend to use him as a trap/lead to Natrin's Barrow, but did not realise that Rand would just BF her in the face (even Ramshalan's POV wouldn't have told her that, or she would have just left). And if she really wanted to cause him pain, she would have just left before he Balefired the palace, so Rand would have seen that he killed hundreds of innocents for no reason. It makes more sense that she forgets that he plays mind games too, because she's made that mistake about Sammael and Moridin already.

2 - Moridin used one of his mindtrapped FS to plant Compulsion leading to Natrin's Barrow in Kerb's mind. Moridin has far more means and motives for the events that occurred than Graendal.

3 - Graendal planted him there as a low-visibility tool to kill off the high-profile Domanis to cover her tracks.

4 - Graendal wanted Millisair dead so it appeared to the other powermongers in Arad Doman that Rand was a brutal king who would kill them too, thereby distancing them from him (her direct orders from Moridin).

5 - Kerb had been planted there ages ago, and Graendal had simply lost track of him or forgotten to tell him to stop killing people.