Although I still lean heavily toward the idea that the message was written by Jack ( due to the fact that I can see no acceptable reason why he would have taken a piece of cloth away from the scene other than as a 'signpost,') I think that a possible explaination could be that the Ripper was considerably more educated than your average Whitechapel inhabitant. I'm not talking a Prince here or anything like that but maybe someone like Druitt. Not necessarily Druitt himself but someone of his education.
Yes, and Druitt worked as a barrister. If we take Druitt as an example, hypothesizing that he wrote the GSG, we can hypothesize that he wanted to act as a judge instead of a barrister and using that title in the GSG.
The spelling of 'juwes' and the double negative could just be an attempt by the killer to appear less educated. Someone would only feel it necessary to hide their level of education if it was noticeably better than everyone else's in the area and they felt that it may give the police a possible clue to his identity.
On the other hand, if Druitt had a reason for communicating with someone he knew and wanted the communication to be clear, he would not intentionally spell the word wrong.
The variation in the sources is the problem and that problem is with the ones who constructed copies of the GSG.
Especially if he lived locally. Say a highly educated man who had fallen on hard times. A resentful man who sees immorality everywhere and blames the Jews for the fact he has to live in such a horrible place.
I would really like to understand why a serial killer would kill destitute women if his actual target was Jewish men. Please explain this to me if you can.