I agree that this type of misspellings seem phony. They are not the common types of errors that people typically make when spelling. Then again, I type badly when I am in a hurry and make spelling errors although I know the correct spelling.
However, when I read the letter it reminded me of my ex-husband. He was raised as a witness and I was "worldly". I studied and became a witness just like this guy hopes. Nevertheless, eventually the truth about the truth wound up tearing our marriage apart. We both still agree that if it had not been for the JW's teachings and imposed guilt we would probably still be married. However, the sad thing is he still defends them and feels that he is the one who is unworthy.
So whether this letter is real or not, it was written to sound real and sadly enough it hits home as I am sure that many others out there are struggling with these same feelings of unworthiness and fear.