I decided to go ahead and cut the adventure out of the Gaia book and just make it more of a simple rehash of the original setting material. After all, the same reason I wanted to cut Gaia out of E&E (if I'm not playing in the setting, that part of the book is deadweight) applies to an adventure in a setting guide (if I'm not running the adventure, that part of the book is deadweight!).
That means, of course, that I'm essentially done with the 2nd book already:
World of Gaia Campaign Setting
And now I can worry about fixing Retro Phaze. But maybe not until summer gets here. I'm exhausted.