When talking about accuracy being a sign of a false Prophet, whenever there is “human choice“ involved in the word, the Prophets are accountable and should be judged on giving the word accurately from God. They are not responsible for how the people respond to it. No one can control free will or guarantee the actions of someone.
A great example of this is Jonah. If you look with natural eyes, Jonah missed it, and the city was not destroyed. We know why it wasn’t destroyed, the people repented!! God changed His mind, and Jonah didn’t do anything wrong; in fact, he knew the entire time God wasn’t going to destroy it.
It is a prideful heart, and you could be coming against God Himself to speak out that someone is false based on your ability to see the outcome with your natural eyes. Remember, people, through their natural eyes, thought Jesus was a carpenter. You must discern spiritual matters through the spirit, not the natural!