The first thing to do is grab the 2007-07-30 update at
https://www.mobileread.com/forums/showthread.php?t=11786 and update your BD.
The next thing to do is to use Book Cleaner to fix the loading of your source material. Download the Book Cleaner files at
https://www.mobileread.com/forums/showthread.php?t=11649 and setup Book Cleaner with these two files. You want version 1.3.
Also set your language to German. If you see any source that isn't German, set it to German and save. That way you'll keep accents on load.
As for the book you are working on, you'll need to reload it to fix the emdashes. You might want to start over in order to fix your emdashes. That means reloading the source and starting from scratch.