Ken Wilber has an excellent account of these things in his books. Yes, in order to "achieve agency," all 4 quadrants need to be considered: individual inner experience, individual external behavior, collective cultural values, and collective social systems. There is no "me" without "us," as personal identity is shaped by and interwoven with cultural and social contexts. Ignoring any quadrant leads to an incomplete understanding of oneself and the world.

Another interesting insight from the same author is that higher levels of development are initially perceived only as symbols. As a human being evolves, these symbolic representations transform into direct experiences of reality.

I am not quite sure what you mean by "agency." Undoubtedly, language enhances the capacity for agency, but it's not absolutely required for all levels of consciousness.

Your thought seems to be a reasonable approximation for the typical midrange of human development stages. I can't speak for the "enlightened" stages, as I am not there.

PS. 'and we can only think in our mother tongue.' - really? This does not sound true. Where you have got this fact?