Okay, so. First things first: power and propulsion. Everything else is secondary.
Basics Powerplant Family: Easy. Steam engines are very simple and the most complicated part is phlogiston chemistry and electricity generation.
Propellers: Easy. Just a copy of designs already in use, and the design poses no significant engineering challenge.
We could do these two, and be fairly confident of getting decent kit, leaving us with plenty of design actions to spend on other tech (sensors, weapons, etc). It would also probably be relatively cheap stuff. (Let's call these tier-one tech)
An alternative option would be to do something a bit more experimental- target of Normal/Difficult (tier-two tech, as it were). If such a project succeeds, then we'd be skipping a tier, which would save actions in the long run. However, if they fail, we'd have to spend a second action to fix them (at the end of the day we'd still be spending two actions for tier-two tech, though). And it would probably be more expensive.
I could see going down either path. I think I'll write up designs for the second option, to get a difficulty check if nothing else.
E: Okay, I dunno if I went too far off the rails with this one. It may conflict with existing lore, for all I know. Iris, plausibility/difficulty check please:
Enlightened Propeller:Long live House Sorlaria! Now that we are free from the repressive yoke of House Nitidid, we can finally unleash the true potential of our greatest minds! After a brief recovery period, our technology will far outshine that produced by the conservative engineers we left behind. Take a propeller. It's just a propeller, right? Not much that can be done to improve it, right? Wrong! Just look at the hominid designs- so much less efficient than our own ducted propellers. Why shouldn't it be possible to improve even further?
Aetheric currents are the topic of much speculation. Where do they come from? Why do they flow the way they do? Eccentric scholars of House Sorlaria have studied this phenomenon, and while they can't answer every question, they believe they have uncovered a relevant piece of the puzzle. They believe the currents are created by the stars, specifically the interference of two (or more) stellar frequencies. The discordance is unnoticeable to all but the most sensitive electronics, but the Aether is affected, creating currents. They can't quite explain why, or indeed predict what effect any particular confluence of frequencies will have, but the basic idea- that interference between two stellar frequencies can cause Aetheric motion- is enough to start with, the rest is just trial and error.
An Enlightened Propeller system consists of a standard ducted propeller, but the blades are coated with a special non-reflective paint. Then there are two 'stellar frequency projectors' (a contraption of mirrors, lenses, and various electric (heat/light/uv)lamps) that shine on the propeller, carefully calibrated so the interference between the two beams happens on the propeller itself. The intended effect is for the propeller blades to interact more strongly with Aether, giving greater thrust than an unenlightened propeller of the same size and strength. Though the frequency projectors require a non-trivial amount of power themselves, overall the system is expected to be considerably more efficient.