The problem with the SSPX is that in order to deal with what they asserted was infidelity, they topped it with more infidelity. And that's where they fell down.
Thankfully, we have the FSSP. They have a church locally (with the full approval of our late archbishop, who dedicated it personally with the full and complete Latin rite) and they are straight-up orthodox shepherds.
So you are saying that Archbishop Lefebrve didn’t read the actual documents before he made his stand against them? Do you really think he would take such a bold stand without doing so?
As for the so-called loopholes, do you find such loopholes in pre-Vatican II documents?