Why would a person creating a document out of layers split individual words and sentences across multiple layers, seemingly randomly (see my post above for an example)?
One reason: if the forger were unhappy with his results for some parts of the text he was forging, and had another go at those parts. In that case, those parts would end up in a separate layer. (I should add that I have significant experience in editing imagery for (legal) use on the web, and have practical familiarity with the vagaries of layer generation during such editing).