Those who deny Mary the title "Mother of God" necessarily deny that Jesus Christ is one divine Person, the Son, the Second Person of the Trinity. They will say, "Mary is the mother of Jesus, but not the mother of God." And if you let them talk a little while, sure enough, they start digging the hole deeper and deeper, talking about Jesus and God the Son as two distinct persons or two distinct beings. They have done so many times in history, and here on FR.
Have you put the Holy Spirit on notice about His short comings in inspiring Scripture?
Are you going to accuse Him of heresy as well?
Do you believe in the Trinity?
If Yes, does that mean the Holy Spirit dropped the ball?
No. It does not.
Other Catholics have done that by denying His Word as being the Truth.