The scene involves a bit of "cheating". Brandon chose to have the action in the scene go on but started hiding from the reader important chunks of Graendal's thought process. Why? Because he didn't want to kill suspense by flatly revealing that Graendal took into account the strong possibilities Rand meant to strike from afar, if she was "lucky" with balefire which would allow her to fake her death with Delana/Aran'gar. Another aspect of the plans was to make sure Aran'gar wouldn't follow her. Another thought that may have crossed Graendal's mind is that if Rand entered the palace, he might strike at first sight and mistake the lascivious Aran'gar for Graendal (Graendal didn't know LTT in Rand would recognize her on sight).

Jordan tended to avoid those cheats in POV, or disguised them differently. He might have chosen to end the scene with Graendal thinking now she had a plan, and have her ask if Delana knows compulsion, then switch to Rand's POV. Graendal would then have justified what she has done only in the aftermath scene. Even more typical of the way Jordan wrote Graendal in particular would have been to give clear signs she's puzzled stuff out and had planned a counter, without revealing what she really thought. E.g. instead of mentionning the risk of balefire straight out in the POV, allusions may have been made to Rahvin. The change in storytelling style made it less obvious to "decode" what was going on in Graendal's mind, when we're so used to Jordan's Graendal POVs.

Graendal has feared Rand tracking her down and coming at her with balefire like he's done to Rahvin since his surprise attack on Caemlyn - and she had long taken the decision she wouldn't confront him but flee if this happened. She once - presumably - took the risk to hang in the Caemlyn palace (where she bumped into Asmodean by chance and killed him) to make sure Rand didn't plan to come after her.

Of course the possibility balefire was on her mind. Two Forsaken had already fallen with balefire - and as far as Graendal knew, maybe Sammael as well.

When she saw Rand had the AK, a weapon she found little less dangerous than balefire itself (which confirms she had the threat of balefire on her mind at that point), of course Graendal considered the possibility Rand might not come anywhere near her to kill her. She doesn't lack courage. She saw an opportunity she might manage to make Rand believe he's killed her, and she took the risk to stay a bit longer to implement her plan.

Another important thing is that Graendal had spies all around Rand and as a psychiatrist understood better than most his state of mind. Rand wasn't realizing he was bordering insanity. He thought Graendal would never consider he could strike with brute force because LTT would never have come at her this way. Graendal saved herself because she rather expected she was dealing with a madman carrying a doomsday device and anything was possible...

Bottomline: Did Graendal considered the possibility balefire would be used and made Delana compel Rand's envoy to fool him it was her who died? Yeah, obviously. Was everything well integrated in the scene as Brandon wrote it? No, it wasn't, or at least Brandon didn't write this episode in a way similar to Jordan's style to handle events like this.

But there's still no question Graendal to a degree expected balefire was a strong possibility, enough to take the risk to stay a bit longer to implement a plan to make advantage of this if it turned out to be true.