It's a known fact that some maps make the race converter sad, specifically if it contains objects outside the 8192 coordinate limit. To fix it, you need to mass-move the map closer to the origin before the conversion process.

Here are a couple of Wurstfinger's maps that I've managed to fix; if you have other maps that need fixing, just tell me which maps you need, and I'll see if I can pull them from my library.