To my knowledge, the technology to begin terraforming anew is lost, though the means to maintain the existing terraforming technologies (some elements of the process require upkeep, such as the towers maintaining Earth-normal gravity on Luna) is carefully preserved.
Game Development - 2D20 System
System Design - Star Trek Adventures
Cyberetronic has begun terraforming Ganymede (Core page 24). But according to Imperial page 83 Ganymede isn't terraformed.
So yes, Cybertronic has the tech but has been thwarted by Imperial with the Brotherhood's blessing. According to Whitestar the terraforming process is deadly to all existing life.
MC3 homebrewer. Check the thread!
CA-138 Deathlockdrum - when you want to put a grenade launcher on a grenade launcher, so you can launch grenades when launching grenades.
I think they still can. In the Dark Legion campaign book, players get to a new colony in the asteroids in search of an item. There's some machines that where recently installed there for terraforming. Also, doesn't the spaceships use some modified form of that same technology to recreate gravity and atmosphere. From what I gather, the present technology is probably a lot less effective than the one before the fall and terribly expensive. its terribly expensive to do and constant watch for corruption is advisible.