I always sort of thought that the guy in the manual is not the same person as the guy in the book, just another guy who happens to write a journal. He strikes me as MUCH more 'Croakeresque' with his "I didn't get his name either..." stuff...
Also, despite him saying it is the seventh year in the war, there are journeymen around so it must be not counting the fall of muirthemne... but it happens MUCH earlier than the game begins, though its possible that they are the same person, that man would be rather old after fighting through the first 20 years, though he does speak as a vetran.
which brings up
We know the 'great war' consisted of 20 years, but I had always assumed that this meant that the West had been fighting the fallen for some 20 years at the beginning of the game, holding them off of madrigal for 20 years. I sort of get the impression that there would be a timelong like this...
Age Long Past Armies of the Dark Came Again Into The Age Of Men>(Mayhaps a hundered years ago) then an unknown amount of time passes (but enough for it to be an age long past) the Dark finally conquers the cath bruig empire, then 20 years before the beginning of the game they start assulting the west... 7 years into that the Manual Journal is written, 20 years after that the game begins...
On a side note, from perspective I would guess that the narrator in the intro is not the same person as the journal writer too, because the journal writer did not realize that it was the same army of the dark as previously in legends until after alric explains in the last few missions.
Either that or the intro is from the journal writer, but after the great war is over...