The first section you quoted from the WCF refers to Adam's condition PRIOR to the fall. The last section clearly denies free will exists.

The human nature prior to the fall is not predetermined to good or evil. But that does not prove that Adam had two equal choices as the libertarian free will view espouses. God has free will but does God have the liberty to become the author of evil acts? Not at all. So the natural liberty you refer to in Adam does not and never could say that Adam had "libertarian" free will. Adam was free from original sin or any corruption of nature prior to the fall. AFTER the fall the human nature IS predetermined to wickedness:

And GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually. (Genesis 6:5 KJV)

Notice that the divine image that is totally corrupt is the "thoughts of his heart." The divine image and likeness of God is rationality and the ability to think. After the fall the noetic effects of sin has corrupted man's ability to reason properly, which leads to all sorts of evil.

As he thinks in his heart, so is he. Proverbs 23:7

What brings about transformation is the knowledge of God's Word. The Scriptures are the instrument God uses in the effectual call. Romans 10:7-17. Acts 4:10, 12. Matthew 22:14

For "who has known the mind of the LORD that he may instruct Him?" But we have the mind of Christ. (1 Corinthians 2:16 NKJ)