Hi! I am Michael Wolf, the guy who translated most of DS into English. Although I can't speak for Christian Kennig, who created DS, I know enough about the game and the license it uses to answer your question.
You are free to do anything with Dungeonslayers as long as you make sure Christian Kennig is properly attributed as the creator of Dungeonslayers. You also have to share the dataset under the Creative Commons 3.0 Attribution-Share-Alike-Non-Commercial license.
When you want to sell the dataset or make it available under another license, you'll have to ask CK for permission. Why not post at the
official forums about your plans? I am sure there are a few people who might be interested in helping you.