G.W. Leibniz Does Not Believe God Causes But Rather Permits Evil

 For Leibniz Evil is merely permitted.

"We can say also that God wills everything that is an object of his particular volition. But we must make a distinction with respect to the objects of his general volition, such as the actions of other creatures, particularly the actions of those that are reasonable, actions with which God wishes to concur. For, if the action is good in itself, we can say that God wills it and sometimes commands it, even when it does not take place. But if the action is evil in itself and becomes good only by accident, because the course of things (particularly punishment and atonement) corrects its evilness and repays the evil with interest in such a way that in the end there is more perfection in the whole sequence than if the evil had not occurred, then we must say that God permits this but does not will it, even though he concurs with it because of the laws of nature he has established and because he knows how to draw a greater good from it." - G.W. Leibniz, Discourse on Metaphysics, Page 7

On Equal Ultimacy

Both good and evil are caused by God. There is not in this world a single thing that befalls which is not in God's absolute control. God is sovereign over the elect and their way of life as he is also sovereign over the reprobate and their way of life.

Proverbs 15:3, Romans 9:15-18, God blinds the Jews - Romans 11:25, 2 Corinthians 3:14, Romans 1:24 which states that God gives people over to a wayward life, Joshua 23:14-15, and also Nabal's heart was hardened and died ten days later from hearing the news - 1 Samuel 23:37-38

In what sense is God the Author of sin?

Jerome Zanchius seems to suggest that God is the Author of all things including sin abstractly speaking. However, God is not the author of sin as one who does the sin.

"God, as the primary and efficient cause of all things, is not only the Author of those actions done by His elect as actions, but also as they are good actions, whereas, on the other hand, though He may be said to be the Author of all the actions done by the wicked, yet He is not the Author of them in a moral and compound sense as they are sinful; but physically, simply and sensu diviso as they are mere actions, abstractedly from all consideration of the goodness or badness of them." - Absolute Predestination, pg. 31 - 32

God is the author of sin

When we are tempted and we sin do not say that God is to blame for your sin or evil lust. Although, He is the author thereof, he is so only on the ground that he is the primary cause of your evil lust and action. However, God is not the author in the sense that he is the one who does the evil lust or action. In the WCF God is the primary cause who uses secondary causes chapter 3.

"1. God, from all eternity, did, by the most wise and holy counsel of his own will, freely, and unchangeably ordain whatsoever comes to pass: yet so, as thereby neither is God the author of sin, nor is violence offered to the will of the creatures; nor is the liberty or contingency of second causes taken away, but rather established."

As for the verses, the Bible says in several places that He sends an evil spirit to some people. Also it says that he caused others to sin so that they would die. He causes kings to go to war. I think he sent a lying spirit to one so that he would be consumed.
I should probably define Authorship if I have not already. Authorship can be denoted in two ways. God is the author of sin in the sense that he actually causes others to commit sin but he himself is not the one committing such acts. Or you could say that Authorship relates to the one who actually did the act. Obviously God did not do the evil - though he is the primary cause of sin he is not the secondary cause of it.I already said he is the author of sin in the sense that he is the primary cause of sin but he is not the doer of sin - the secondary cause.
The problem with permitting sin is that it does not remove God from responsibility. For instance, Augustine is known to say that Evil is just the absence of good. But if this is the case then why did God remove himself from the situation?

"Israel also came into Egypt; and Jacob sojourned in the land of Ham.

24And he increased his people greatly; and made them stronger than their enemies.

25He turned their heart to hate his people, to deal subtilly with his servants.

26He sent Moses his servant; and Aaron whom he had chosen.

27They shewed his signs among them, and wonders in the land of Ham.

28He sent darkness, and made it dark; and they rebelled not against his word.

29He turned their waters into blood, and slew their fish."
- Psalm 105

This verse does not say he permitted the Egyptians to hate his people but that he turned their hearts to hate his people.Yes, he causes sin. He also hardened Pharaoh's heart so that HIS purpose would be fulfilled.