"In the best case scenario, that of a truly ecumenical council in the traditional meaning of the term, i.e. actually representative of an undivided Christendom, the most that divine assistance can ensure for the Apostles' successors is the absence of any possible error in the doctrinal definitions such assemblies venture to produce. But, short of this extreme case, any dosage of approximation, insufficiency, or simple superficiality are to be expected from even so sacrosanct an assembly.
"What then is to be expected from simple local councils, not to say anything of episcopal conferences regularly manipulated by more or less irresponsible offices, or of assemblies of so-called 'experts,' or of any other such commission!
"If the Church derives anything of value from them, it is only that which the highest 'responsible' persons (as they are called these days) in the apostolic succession, popes or influential bishops, will sift out, be it by the importance of their sees or by their recognized merits, from its more or less adequate husk and asides.
"Still, it is up to the sensus communis fidelium—understood of those who truly are such ['the faithful']—in the final analysis, to make it its own and, at that level, to make it positive and effective by the benefit they will derive from it in the sphere of the only spiritual progress that counts: that towards Gospel holiness."
Louis Bouyer, The memoirs of Louis Bouyer, trans. John Pepino (Kettering, OH: Angelico Press, 2015 [2014]), chap. 12, p. 215-216. Earlier on p. 215 Bouyer had spoken of "incompetence, intrigue, the smoke and mirrors thrust in each other's way", and cited Gregory of Nazianzus via pp. 367 ff. of Ratzinger's Principles of Catholic theology, which is very good.