Preliminary thoughts: Thinking through the writing of the Popul Vuh makes me think more about languages and also the writing of the bible.
OK, the Popul Vuh was written by Francisco Ximénez in the early 1700's after living with the Maya for several years (no one is quite sure exactly when which parts were written). His extensive time with the Maya would have allowed him a good command of their language, though not quite at the level of a native speaker. Our understanding of this book is reliant upon Francisco's command of the Mayan language Quiché. If Francisco misunderstood a key Mayan concept, due to this language barrier, we also will misunderstand that concept when reading the Popul Vuh. Surely some meaning was lost/changed when Francisco converted the Popul Vuh from Quiché to Spanish.
Another concern is the fact that Francisco was a religious dude, a priest in fact. In his prólogo, he mentions the Catholic faith, mentions the holy scripture, and he mentions satan. This makes me wonder if the Popul Vuh might have been translated differently from the eyes of a Buddhist, or Hindu, or atheist, for example. Surely Francisco's Catholic background had some influence on his translation of this Maya history and culture. (Just keep this in mind when you read the words "heaven", "God", etc in the Popul Vuh - these words might be more from Francisco's rosy-colored-glasses perspective than from the actual Maya). Some historians even wonder if the Maya story itself had changed somewhat from their earlier (pre-Western) days due to the presence of the Catholic missionaries and their "pressure" to convert to Catholicism.
Additionally, some meanings are changed (slightly) when translating over to English (for example, even modern-day translators will come up with different translations given the exact same script in another language). So, bottom line, what we read now in English (and even in Spanish) is perhaps not the "true" Popul Vuh, but the best estimate of Mayan customs/traditions/religion that we have.
This, of course, parallels the writing/translation of the Bible. If John of Patmos misinterpreted his vision, that is one source of error/misinterpretation of Revelations. Another source of error/misinterpretation is the translation of Greek to English. Yet many Christians today read the english version as if it were the literal "true" word of God.
Another parallel is the sometimes difficult translation of the Buddhist sutras to English or the Tao to English. Some ideas/thoughts/sayings in a certain language are nearly impossible to translate over to another language, some meaning is inevitably lost.
OK, on with the study! Just wanted to toss out these thoughts from a language perspective...