I found a few things that could use some fixing/adding.
1. If you follow the directions for Book Cleaner in the em dash section, you won't be getting any of the other fixes in the Book Cleaner files I've posted or if you already have my Book cleaner files installed, following the directions will stop them from being used. The best solution is to create a section that tells peopl eof my Book Cleaner files and how to install them. They will fix the em dashes as well as -- to em dash as well as a number of other issues.
2. If a text file is loaded into Book Designer, there is a chance that some of the paragraphs can end up messed up. I don't know why this is or how to fix it. But the solution is to load RTF or HTML. So if you have a text file, load it into word and save it as RTF and then it will load without the paragraphs getting messed up.
3. When creating a book in LRF format, the default for Book Designer is to have the main text bold by default. I notice a number of eBooks here have or had bold body text because of this.