Just from a mod design point of view, the final Constitution and the first Excelsior are 'technological peers' (at the same tech tier) and they are in the same 'weight class' (both Cruiser-sized) as well, so it is expected that they are roughly equivalent, though not identical. The final Excelsior should be much better than the Constitution, though.

All of the ships in the mod follow a rules-based system, most of their properties are defined by their tech tier and size. Mostly it's the weapons that are customised, but those also follow a set of rules.

You can definitely change these things if you like! Check out STNC_scripted_variables_ships.txt if you want to play around with the values.

It's kind of tough though, because the Constitution is listed as a Heavy Cruiser, but really... Should probably be a plain Cruiser or Light Cruiser at that point in time.

Balance between game and lore.