This will be my last shot at this, Kevin.
<< the question was is God's Word inviolate?>>
The answer is: By definition, private revelation is NOT the Word of God.
The question the church tries to answer is different: Is a claimed private revelation consistent with, or at least not at odds with, Divine Revelation as it is understood and taught by the church? If the revelation is found to be at odds with Divine Revelation, the faithful are warned against it. If it is found not to be at odds with Divine Revelation, the faithful are free to appropriate what helps them and to ignore what does not help them.