The scylla wasn't actually designed by the rogues nor mollies either- "the best minds available were recruited at gunpoint and put to work with utmost secrecy to craft a capital class vessel capable of defending critical infrastructure against the heaviest of hostile incursions". From then, they mostly just have to gather the resources and put it together, as well as maintain, repair and crew the vessels.
I do agree that the planets/moons are fairly unrealistic, especially in terms of scale- but hey its a game so you gotta go for what works and is fun, over what is more realiistic i guess
