In volume one, it seems that only half the words of the original are kept. M.A. Orthofer reports:
Beijing University teacher Liu Yiqing is quoted:
“There is still something we can improve in the way the footnotes are presented,” she says. “While putting every possible meaning in Chinese into the text, it will break the integrity of the story. We should make it a story that is also interesting for college students to read and understand.”
Also via Orthofer, here is one measure of which is the most frequently liberated book.