"Yea, I make a record in the language of my father, which consists of the learning of the Jews and the language of the Egyptians."
Otherwise known as modified or reformed Egyptian this record is written in a language that under most circumstances could not be translated except by the power of God.
These records were written and handed down generation to generations, adapted by the way of speech used by the people. by keeping the language as consistant as possible they were able to share the words of God through the many years that make up the Book of Mormon. And through the use of the Urmmim and Thummim they were translated and we now have these scriptures today.
Jews language record how? Change Egypt language. Happen, year+++ generation+++ same language have. Language same have share God His word can. Book of Mormon language same year+++. Translate how? Urmim and Thummim can. Scripture have now can.