We have such different perceptions of God, there may not be a meeting ground. You seem to think God knows what is going to happen before it happens.
Let's start with what we do know which is mankind wanted to know both good and evil. Did the teen girls know they were lying? Absolutely. And they knew people were being put to death based on the lies they were telling, the performances they were exhibiting. As for the adults: When they accused a four-year-old of being a witch, the little girl was put into a dark, unsanitary prison cell where over her months of incarceration she slowly went insane and never recovered. Girls may have accused her, but adults threw a four-year-old into a jail cell, mistreated her, barely fed her. And you want to blame God?!
Let's look at the other side where humans also wanted to, like God, bring goodness out of evil. In the case of Salem, evil was all around them and prevailed for months where many good people seemed at a loss for way too long. And the evil was being stirred up by mere children--although, admittedly, too many adults were eager to take advantage of the situation for their own power and monetary gain. Evil, power, and money against the rest.
You believe the answer is for God to step in. Wouldn't that have the people crying, "No fair! You said we could know evil!" Wouldn't the people who want to learn how to bring good out of evil begin grumbling how can they learn to do this when God is always stepping in and whipping things back into shape before anyone else even has a chance.
What say you? Do you want to know both good and evil, or would you elect to remain oblivious? Do you want someone else to dress and feed you, or would you prefer to learn to do it yourself?
My question is why does it take us so long to turn evil to good? As far as Salem goes...there is the point that the witch trials ended far sooner than we were able to end slavery.