Greetings, glad to see another believer of aesthetics in carrier design! I've taken interest with your ship designs and I'd like to advise you on a couple things regarding the sprites;
For starter, I'd reckon a tad bit of shading and lighting would do you nicely to bring out the shape more. From what I understand from looking at the carrier, it felt like a triple decked ship akin to the one you'd recognize from Space Battleship Yamato anime series. If that's the case, I think some faint white airbrush lighting around any area you deem higher than the rest would be recommended. You should also apply soft shading around the edges of the bridge to make the shape pop out if you know what I mean, oh and lighter green within the same area of course!
That's all I have to say for now, I think the others may also need a bit more refurbishment using the same technique as I mentioned above. Feel free to reply back to me if you have any questions or would like me to assist you in some ways. Good luck with the mod!