Yep, I'm not sure why this map in particular gave me issues when splitting it, I had the same issues with another outdoor map but managed to fix that one. I'll take a look at it and see if I can get it working correctly.
Currently, To gain access to that map you need to first find the files for the Day map, recombine them into a single image, fiddle with the colour balance, split the image into little squares, put those files into the right folder, then link the area to the world map, and code in some way for your characters to gain access to the location in game - usually by dialogue... or you wait until I've had some time and inclination to do it myself.
It's probably different resolutions of the master images. IIRC, WB will only parse a specific resolution correctly.
That might explain why I tried to get this map working at least 3 times and still couldn't get it right.