Lefebvre and the others listed in Ecclesia Dei were/are schismatic. Your defense of them is odd.
They specialise in opposing the Pope. They exercise ministry absent Jurisdiction. Their marriages and confessions are invalid.
They have set-up their own Magisterium, their own Canon Law rules and they undertake to issue annulments etc. You may buy their duplicitous lies but few real Catholics do.
You keep citing a source that is from an appeal for reunion. It will NEVER happen while Williamson is alive. Frankly, I think the SSPX is engaged in an enprmous dog and pony shopw and they have NO intention of reuniting unless the Pope accepts THEIR demands.
Despite what they say publicly, they think they are the Remnant and Rome must capitualte to them.