I'm kind of worried about making plans even shorter for bonus XP than they already are, because of the risk of something tersely worded being misinterpreted in a way that we wouldn't want if the resulting text were given to us ahead of time and that resulting in consequences ranging from the inconvenient (like the 'wait Kagome didn't know we were giving Jiraiya the seals he taught us?') to the disastrous. (Like the killbox incident.)
300 words is more than enough so long as you maintain focus. Stick to 1-3 scenes and you're fine. Spread your wordcount out over nine scenes and you're not.
I doubt the QMs would do something like that now. I think feedback over time has helped them get a better grasp how to implement plans and the sorts of things that will surprise and upset the playerbase because they didn't intend for Hazou to act that way.
We absolutely would do that again.
We don't like having to deal with player salt; it's unpleasant for everyone. That said, all three QMs feel very strongly that the entire point of a rational quest is that bad things can and will happen if the players make mistakes -- exactly the same way that good things happen when y'all make good decisions. Let's review; you invented skywalkers and decided[*] to barter them to Leaf, so:
* The entire political and military balance of the Elemental Nations was upended during the Ultimate Showdown of Ultimate Destiny -- Hiruzen, Zabuza, Mei, and a major part of the Leaf and Mist jōnin were all killed, Naruto and Yagura were captured. Mist has a toehold on the continent that they previously lacked. Mist and Leaf are growing closer and may well end up as allies, assuming they don't jump straight to stabbing.
* You are now effectively royalty, members of the Hokage's clan and heir presumptive to everything the "world's greatest sealmaster, spymaster, and Sage" knows and has.
* Ninja are going out on Uplift missions (till'n'fills) to help civilians. That entire mission category exists because you talked to Jiraiya about it.
That's just the fallout from one decision. More recently, you utterly destroyed the Chūnin Exams because of good decisions by the players. Everyone with an ounce of sense and knowledge of what happened will recognize that Team Uplift are among the most powerful genin of this generation. You should assume that every chief intelligence officer in the Elemental Nations knows your names and as much of your capabilities as they can tease out of what happened.
So, yes. Incredible things can happen when the players make good decisions. By the same token, equally bad things can happen if y'all make bad decisions. The killbox didn't happen because the QMs misunderstood anything, it happened because the players made a bad call. Now, after that was over there was a mutual (QM+players) decision to give Hazō some agency in order to smooth out places where he would have access to cultural information that y'all don't. That's not the same as him saving you if y'all vote for something unwise. If another plan like the killbox gets voted in, we will absolutely write you getting thrown into the killbox again, and it's unlikely that you'd get a third chance.