Your error, Stubborn, is in limiting the general protection of the Holy Spirit over the Church and over the entire body of the Magisterium (infallible or not). You would limit this protection and guidance of the Holy Spirit to the 1% of Catholic doctrine that has been defined dogmatically in teaching that meets the notes of infallibility. For you, everything else is up for grabs and capable of becoming thoroughly corrupted, along with the Public Worship of the Church, the Mass. That is not possible, despite your quibbling over the precise limits of infallibility in the strict sense.
I'm not limiting anything, there is no teaching of the Church that teaches all Councils are infallible. What the Church does teach, as I posted, is that definitions within Councils are infallible, which agrees with the dogmatic definition of papal infallibility. "...it is a single, as it were, a single cloth woven from the top so that there are no seams, there is a perfect unity."
V2 defined nothing and had no intention of ever defining anything.
The idea that all Councils are infallible is NO and is an idea that is only in perfect unity with LG 25.2.