It's rather obvious it was, even more where it was to happen in the drama, and the ingredients involved.

Aran'gar was planning to meddle with Graendal's agents, and try to kill Rand. Graendal was ordered to frustrate Rand, but not to harm nor kill him.

Rand was going mad, made a serious mistake that jeopardize the Pattern to kill so many people at once with balefire. He missed his target, and her danger increased because Rand now believes her dead (when she returns, he might also conclude wrongly Moridin manipulated to him about balefire being the key to the final death of the Chosen. It's doubtful "New Rand" has the same view of using balefire than he had pre-epiphany anyway. In the WoS, he was First Among the Servants and War Leader, and most likely LTT is the very person who forbade the use of this weave in any circumstance anyway, without even any garantee the Shadow would do the same. When you fight for the survival of the Pattern, there are things you ought not do, and using balefire is one of them. LTT could never control which AS, and how often, would suddenly decide it was absolutely necessary to use BF, and when these "absolutely necessary" uses would end up unravelling the Pattern. Such a weave should never be used by anyone, period, every use of it is a complete gamble... for instance, with the Pattern in such a state, what would happen if someone balefired the person who kills a ta'veren as powerful as Rand, who binds thousands if not all threads in the Pattern? When Mat was killed and brought back, he didn't have many followers yet. Now, balefire to save one of the trio might very well unravel the Pattern. No single life is worth the risk of balefire, especially now, and even more after the seals are broken and Shai'tan's touch on the Pattern weakens it even more ).

In the context, Graendal's survival made perfect dramatic sense, and her death would have contradicted the motifs and themes being developped for Rand. It heightened Rand's failure, and that he had totally lost sight of the greater picture, and it was worse because Rand had thought himself so right, and so clever... and proved so wrong. Had it not been for Delana and Aran'gar that provided and opportunity to turn the tables on Rand, Graendal had seen through what he was doing, and she would have done what she always said she'd do if Rand came for her: abandon everything and flee. It also added some irony, as without knowing Rand still got rid of a Forsaken who was planning to kill him and was perhaps to be the greatest threat to Rand in AD, by her planned meddling with Graendal's agents.

I don't think Brandon changed much of the story points planned by RJ, like when or how the Forsaken met their demise. It's still too early to speculate if RJ truly intended to have Graendal target Perrin. I tend to think, pending better evidence to contradict this in AMOL, that this was an addition by Brandon to spice things up in TOM for Perrin by getting a Forsaken involved (but why not stay with the mysterious one who sent Masema his dream, I wonder... when Graendal herself revealed in TGS that Cyndane and Moghedien were trying to get Perrin and Mat killed from time to time.). The whole plan doesn't fit Graendal's style at all (tough, fine, the last thing she wanted was to leave clues she was still around), and she was hardly needed for all that. Moridin could very simply have tasked Slayer directly with this or have Cyndane/Moghedien supervise it possibly only by implication, and having Graendal tamper with Child Byar was also completely useless, and ruined the character and his ending. The guy was a finished fanatic who would never have seen reason nor accept an alliance of the WC with Perrin. On his own he would have lost it and tried to kill Perrin, there was no need to add Compulsion to the mix. Finally, there wasn't any really need to add a second fiasco before Graendal got punished. Shaidar Haran could perfectly have come for her in her hiding place, and be furious with her for Aran'gar's death and her failure with Rand. Incidentally, having this happen at the end of TOM might have diluted an effect planned by RJ. Semirhage was betrayed and sacrificed, Moridin revealed the secret of balefire to Rand putting all the Chosen at risk, and then shortly later Graendal escaped balefired only to end up mindtrapped (which is an extremely fitting developement... she mindtraps people with Compulsion, and now she ends up as Moridin's pet for failing to make Rand dance like a puppet to her tune in AD. The irony is a bit lost when it happens because Slayer failed with Perrin, caused Mesaana's demise by accident, and she paid for his incompetence... what was she supposed to do, since Slayer didn't warn her immediately that Perrin had found the dreamspike and was trying to move it?). The whole thing is bizarre as a WOT development, and makes me believe RJ probably didn't plan to have Graendal involved with Perrin. She was to survive Rand, and end up mindtrapped, and then Cyndane entered the plot as the next agent sent to Rand, with a last chance to redeem herself and regain her freedom. This makes all the more sense to me when I compare the timelines. Graendal's involvement with Perrin makes even less sense when you consider that would have escaped Rand only to hatch her Perrin plot right away, and fail and be punished not long after. Had the chronology been respected more, Perrin's storyline was very advanced already, almost finished, when Graendal got involved. It's by cheating with the order in which he told the events that Brandon got this Graendal/Moridin scene at the beginning of TOM. That scene took place many weeks later in Perrin's storyline, which opened not long after Malden, and therefore not so long after Semirhage's capture... Graendal got involved only weeks later, and Brandon rather obviously delayed the trap with the dreamspike to make it work, following a mistake of interpretation/continuity (he mistakingly made it so the Asha'man didn't know how to tie their gateways, which is absolutely wrong: it was established by RJ in KOD that they knew how to do it, and Perrin was perfectly aware this was the solution to keep gateways open for hours without tiring themselves up. It was also established in KOD that Grady and Neald had been (insert your favourite explanation here: too stupid, too proud, too inexperienced, had understimated their fatigue and so on) to tie up their gateways before they reached near exhaustion during the hunt for Faile, and that they began doing that only on the eve of Malden. Cumulated channelling exhaustion is a very rough thing, and would leave them unable to channel for quite some time... enough to let them get trapped by the dreamspike. It sounds to me like Brandon overlooked by accident the tied-up gateways, and introduced a big plot hole/continuity error there by coming up with new reasons why the Asha'man could not Travel, so this could be stretched until Graendal could get involved. If you follow what's established by RJ, the whole storyline doesn't work. The dreamspike had to come earlier than this to trap the Asha'man, like a week or two after Malden at most... right when Perrin and Galad met. And I think this is what RJ planned: the Asha'man too exhausted to Travel, and when they finally recuperated and could send the refugees away and Travel to Andor with Perrin, they realized gateways no longer worked, and tadam... Galad and the WC appeared. That would have removed a lot of sillyness from the storyline, like Balwer's calculations, and even the necessity to strech things out and find ways how Galad and Perrin could delay things up for so long before anything concrete happened. Northern Altara was full of Seanchan armies, Galad could not go east. Perrin lost Travelling, so he was trapped - full of Seanchan to the east, and Galad blocking his way to Ghealdan, and with cavalry, not refugees on foot. This sounds more like what RJ might have had in mind, IMO, then stretching things out for a few more weeks artificially, until Graendal was free to come supervise a scheme that didn't need her character involved at all.