**Thus your premise is that ensured perpetual magisterial infallibility is essential for the discernment of what is of God, correct?**
And yet, right here on FR, we see Roman Catholics interpreting the Magisterium in multiple ways.
Which one of them is right or wrong? How are we to know?
What does your conscience tell you?
The God Almighty...who designed everything to function and operate, from the instincts in animals, to the DNA in man, to our entire solar system......who came to earth and embodied a wee baby...endured the cross, died and rose for us.....NEEDS a group of power seeking old men to tell people what his word says?
Nah.