The surface of the paper you choose makes a difference. As has been said, the paper is rolled to get a certain texture, which will definitely affect the outcome of shadow detail. You might try drying the paper, after you acidify it, in contact with a very smooth sheet of metal, such as a ferrotype plate. One of the print dryers that uses a heated metal patten and a cloth to keep the paper in contact with it would work. This flattens the surface fibers and is an old trick of those who make paper by hand to get something that can be more easily used as writing paper.