Of course he signed all documents, because the signature only meens you are present. It doesn't meen you agree with them.
v2 are heretic and condamned
Quanta Cura vs dignitatis humanae
Satis Cognitum vs redintegratio
etc...
I'm quite sure this was never a secret. +Lehebvre didn't dispute Vatican II, only the way it was misimplemented.
+Fellay and the others are now in communion with the Pope.