"Do we really know what LUMEN GENTIUM means?"
Sure, its simple Latin:
Lumen = light
Gentium = peoples/nations/humanity
ergo Lumen gentium = Light of humanity.
"Is this an objective view"
Only if one starts with the premise that it is a coherent text in conformity with Catholic Tradition and free from ambiguity, false philosophical presuppositions and inherent contradictions.
If one tends to the view that this latter state of affairs is not the case, then one could agree that LG has indeed been subverted, but one might propose that the seeds of its subversion are to be found in the text itself.
The inexorable working out of that subversion is the inevitable consequence of the modernist paradigm in which much of the document is framed.
By the very nature of the Church as the Body of Christ ensouled by the Holy Spirit and guided infallibly by the teaching authority of the Pope and the universal Magesterium, the text of Lumen Gentium MUST be a coherent extension and illumination of Tradition. To reject that is to reject the very Tradition of the Church that one seeks to uphold by rejecting the validity of Lumen Gentium. It's a little ironic, but such is schism and heresy.