The Catechism in Questions & Answers

627. Does this rule out any mistakes in the proclamation and hearing of the sermon?

Any human being who proclaims the word of God is a sinner who has weaknesses and makes mistakes. However, the ministry which he bears has been given by God and is therefore holy. If this imperfect human being then proclaims the word of God, it can indeed contain mistakes. Nevertheless, God lays His power into the words spoken by human beings.
The listeners are likewise sinners. They too have weaknesses and likewise make mistakes. For this reason one cannot rule out the possibility of error in understanding that which is heard. If they, nevertheless, accept the word of God in faith, they will be able to absorb into their souls all the divine powers contained in the sermon, despite any human imperfections and mistakes.