Barth tells the story of the Reformed confessions by contrasting their reception with the place of the Augsburg Confession (the 'Augustana') in Lutheranism. The Augsburg Confession was very quickly considered to be on a level with the ecumenical creeds of the Church. The Lutheran Church was still very much wedded to the old Imperial ideal - one Empire, one Church - and so the Confession could hardly be received as anything else. Moreover, the Confession had been presented to the Emperor - albeit only as a protest, since it was not received. It was therefore a public and ecumenical confession, in the eyes of Lutheran theologians at least. It was only a small step from there to the Book of Concord, which upholds the Augustana, along with various other Lutheran products, as the standard of faith never to be shaken. As Barth points out, this leads to the exaltation of the Confession to the level of Scripture - the Formula of Concord makes regular reference to "the Word of God and the Augsburg Confession" as things which are hardly separable. Luther is seen as essentially a new apostle; the Confession is the product of the Holy Spirit.
This should never happen in a Reformed Church. The Reformed churches were happy for there to be numerous confessions, not fixing on one form of words, because they saw that the confessions were the products of particular churches. They confessed the faith which churches had received from the Scriptures. As such they were always in principle open to correction. Thus Zwingli: "where I have not now correctly understood the said Scripture, I am ready to be corrected and instructed from the aforesaid Scripture". Confessions in the Reformed tradition were understood to be provisional, even when loyalty to them was demanded of the church's teachers in the strongest terms.
It seems to me that (if Barth's view of Lutheranism is correct), the Lutheran Church views authority as coming from Scripture, via the Confession, to the Church. The Confession stands above the Church, as a kind of subordinate Scripture. Barth's picture of the Reformed view has authority come directly from Scripture to the Church, which produces the confession as a result of what it has heard and understood from Scripture. Because it is what the church has heard, the confession cannot then be set aside lightly, but it can be modified and even replaced in time.
Barth concludes that we don't have new Reformed confessions of the standard and profundity of the older confessions simply because we do not have Christians and theologians who are being reformed by the Scriptures. Reformed confessions come from Reformed Christians, and Reformed Christians are brought to birth by Holy Scripture.
"The current situation [now as in 1923!] does make it especially advisable that the Reformed church should set its only hope (truly its only hope) on the prayer 'Come, Creator Spirit!'"