I haven't been playing GalCiv2 very long and have only had an occasion to use Orbital Terraforming twice. However both times, it seems to have broken the program. What I mean is, it terraforms all my planets just fine. However, any planet that I capture after building the orbital terraforming loses all its un-terraformed squares. (for example, I click on a planet before I invade, I see that the Torians haven't built Soil Enhancers or anything to increase the number of available squares, yet they have built on all of the normally available squares.
After I invade that planet and capture it, or more often win it over due to influence, those extra un-developed squares disappear. When I take over a class 15 planet that still has undeveloped yellow and orange squares (I don't see the red ones, but I know the torians don't have terraforming) I should have between 3 and 6 extra new green squares. Instead, those squares disappear entirely. only the squares that were developed (or undeveloped but green on the planet viewer the turn before takeover) show up on the planet, the yellow and orange squares disappear entirely.
This only happens after I build the orbital terraforming "achievement". Before the achievement those additional squares are there for me to terraform by hand. I tried saving the game when that happened so I could provide you screenshots, but I accidentally saved over it.