It’s a lovely piece, but maybe goes a bit too far in trying to paint Lem as some kind of human-form planet Solaris himself, failing to communicate with ordinary people. For example:

“These essays are the work of a lonely man. We can judge the fervor of Lem's attempt to reach out by a piece like ‘On the Structural Analysis of Science Fiction:’ a Pole, writing in German, to an Austrian, about French semantic theory. The mind reels.”

That just sounds like an ordinary letter for a 20th century European intellectual. Reading and writing in French and German was table stakes.