Your version did work quite a lot better. The main thing still to fix was derailing on switches, which I fixed by moving the center-most wheels inwards slightly, as well as a few other adjustments. Since the center- and outer-most wheels now have slightly different X-positions, there's now a winch connecting the two bogies together to prevent them from spinning completely around. In short, it now only derails if you're going fast, which is pretty much true of all the other rolling stock made for that map anyway.

I also raised the wheels slightly to lower the couplers so they lined up more with some of the existing equipment, and added some more weight.