What do you think the Holy Spirit's role is in an ecumenical Council?
To inspire and guide. I can go to the doctor and he can provide a structured diet to help me live better. If I leave the doctor's office, ignore his advice, and start eating fast food morning, noon, and night, that doesn't make the doctor or his diet invalid or fraudulent. It convicts me of not implementing it as intended. In the same way, Vatican II and the novus ordo were, as a matter of faith, infallibly inspired by the Holy Spirit. The liturgical abuses which occured IN SPITE OF Vatican II do not convict the Holy Spirit of insufficient inspiration.