(1) Book of Abraham revealed to Smith; he writes it down.
(2) Smith and cohorts create symbols to encipher segments and phrases (a shorthand) because they believed that was typical of language as practiced by the ancients.
(3) This cipher key was used to encrypt "sensitive" revelations to keep them secret before they were all written down. (Why?)
(4) The word "Egyptian" to them was a code word for "pure language" as delivered to Adam by God that was ultimately corrupted, and has nothing to do with Egypt. Somehow, not explained, is that "Egyptian" escaped this corruption.
(5) Therefore, when Adam spoke, a single sound (word) could represent a single word, sentence, of paragraph of over a hundred words.
I encrypt all of this as "Ugh."