Yes, there have been many translations, and there are scriptural books that “did not make the cut” . Follow your logic once again. Who is to say that those men who made such “decissions” were not indeed guided by the spirit?
Indeed what makes more sense, following a line of rational and exact actions over 6000 plus years or throwing in never before heard of ideas and concepts that are alien to all those who have followed the lord for those thousands of years?
Could the record really be that hidden from all of man? Where are the “proto” Mormons, the ones who knew of the Priesthood concept as you see it, the ones who knew of Kolob and the Nephites and Laminates? You mean to tell me that is just 2000 years we lost that until Joe stuck his head in his hat? You talk of "silly', that is remarkable!
You quote Ehrman, a agnostic, who has made good points, but is he more interested in finding fault or finding faith. Is he like so many others so mired in the muck of the details that they can't see the beauty of the meaning?
Just because it isn’t in the Bible doesn’t mean it didn’t exist. Lots of sacred writings were left out of the Bible. The people who assembled the various Bibles looked at the texts that had survived, and selected among them.