I use Landscape Builder to post process RWT generated terrains. Not sure if you are familiar with LB but its a bit like photoshop for terrains. I can import a bunch of terrains and add additional layers like some noise, lower, raise, smooth etc.

LB needs terrains like this
[3][6][9]
[2][5][8]
[1][4][7]

but RWT generates them like this:
[7][8][9]
[4][5][6]
[1][2][3]

if its not too hard to change would it be possible to generate the terrains in that order?