Once more: the John of Jerusalem prophecy does NOT exist before its publication in Paris in 1994. No writer in either French or English has mentioned this prophecy in any books or scholarly articles published on the Crusades or the knight orders.
The editor's name given on the 1994 publication, M.Galvieski, is fake (thanks go to the Russian yogi Maxim for researching this), and 'John of Jerusalem' is clearly an elaboration based on the biography (such as we know it) of Brother Gerard Tonque, the first master of the Hospitaller Knights of the Order of John of Jerusalem, who are in fact named after the 3rd/4th century Bishop of the same name.
In my view, this prophecy cannot be regarded as being from the 11/12th century. It is clearly a late 20th century text. As the latter it is of some interest as Dan Costian has noted.