I like having the battleship be the big FE battlecruiser, but I also like the corvettes of the other one. I think the Ancient Ships mod fits in with the FE aesthetic (which does kinda make sense).

I propose:
Battleship- FE Cruiser
Cruiser- FE Destroyers (Upscaled)
Destroyer- Ancient Destroyer or FE Destroyers (Regular Scale)
Corvette- FE Fighters (Upscaled)
Construction Ship- Ancient Construction Ship
Colony Ship- Ancient Battleship
Science Ship- FE Battleship
Transport- FE Construction Ship