Hey! I looked into this, without knowing what I was looking for, examining the .set file for each tileset. Wildlands has the ability to use ambient/diffuse on an individual tile, while Wildwoods does not.
Upon examining each .set file, and looking at a tile in each of those .set files, I found references of ambient/diffuse settings for that particular tile.
Thing is, they both matched in their input values being = 0.
So, how is it disabled in Wildwoods but enabled in Wildlands, when they are identical? Well, identical from all I could tell by examining their .set files.
Is there a setting in the .set file I could add a line or make a modification to, to enable ambient/diffuse tile lighting for each individual tile for Wildwoods?
If this change requires GMax or some other tileset building tool, I'm out. 
'>
FP!
The main tile lights are defined in each model file. There's no way of turning them on or off in a set file. If you can't use the main lights in the toolset, they are probably missing in the tile models.
If you look at models with NWNExplorer there is an option to show lights. They are displayed as yellow globes.
Now look at the models of the wildwoods tileset and you'll see that the lights are missing.
You can add the lights at their default positions 1.5, 1.5, 4 and -1.5, -1.5, 3.5 for each tile. This can also be done with a text editor, but will get too complicated if the tile has animations. And the lights might not be optimal at the default positions.
To get the best effects you'd have to open each tile in gmax and add the tile lights where they make the most sense which can be at the default positions for most of them, but there are always a few tiles where the lights have to be placed elsewhere, especially if they end up within a wall, rockface, etc.
