Thanks for the answers, they were welcomed and gave me new insight but I still feel we are talking apples and oranges here... although I was probably influenced by storytelling practice from other video games and my own imagination focus, so I guess I won't make much sense without specific description.

In short, the core idea of it was to be able to provide a proper Garlean city encounter without having to invade the empire itself, not to mention the difficulties we will encounter if we tried to do storytelling in a city where we are explicitly the invaders. So the "scientists, engineers, their families on-site, and spies" was supposed to be a rather ideal compromise. We have met lots of Garleans as was pointed out, but we have yet to properly see their cities and their civics.

Besides the civics, the next most important thing (at least in my mind) was to provide a breath of fresh air on the story, either by using pass-tense storytelling of a "mundane" but no less touching story, or by creating a good story arc that is not constantly overshadowed by stuff like eikons, world-saver-all-star-party, etc. aka. focusing more on a "standard" FF type story that does not involve living deus-ex-plot-devices every other turn. It's difficult to describe a more "standard" serious story without giving examples but I'm not sure what I imagined would be looked liberally upon, so I'm not quite ready to share it yet.

Another important thing would be to provide a few key features like underground gardens, Garlean classes and technology on the game and whatever help they could be for the base game, but this is actually not one of my key concerns despite probably a high priority thing to consider in actual production (what features to introduce into the game etc.) I just want a good story. There's plenty of story sure, and none of it is bad per se, but it's just hard to describe the "good" kind of story, and FF story I have in mind.