Hum for your new ships, do you plan to add them just like that or is it only the shape? Coz' that's kinda... Weird?
Played a bit more of Citadels, i think they could be considered as overpowered. The supply cost is negligible, same with the CR cost. Would they have extremely bad ships i could understand, but they are actually close to high-tech levels, especially the weapons.
Are you using Codex 20? That mod is always handy for balancing. I would be surprised if it rate them as balanced right now though (i don't know if Codex can rate the weapons, that could explain everything actually).
Another thing, but that's more a personal point of view here. Why the Citadel system is so far? To get there from Corvus you have to fly like 1 or 2 minute. Personaly i hate waiting stuffs like that, that's why i usually change the positioning of modded systems like the Zorgs, Nomads and Citadels to be closer to Corvus.
Then again i repeat, it's a personal opinion and if there's some lore explanation for the distance, it's fine for me. It's just that i find boring to have your system on the edge of the map as the player won't often go there.