With regard to punctuation, I would never suggest that fanfic authors should imitate that of Austen. Punctuation was not standardized and can be somewhat confusing. And yes, it was probably the typesetters who were responsible. I enjoy most stories on this site. I admire people's imaginative creativity in concocting new plots and back stories. As long as the writing is clear we should be satisfied. If some achieve that with shorter sentences and others with longer ones, who cares? But if you wish to sound like Austen you might study her style and come to enjoy it.