The Shivans aren't actually renowned scientists. They did use Lucy 8000 years ago, so as far as I'm concerned they don't really care about progress. They care about wiping out civilizations.
So there!
yeah, if you think about it, they really don't have anything new on their ships besides the beams and flak.

They might be changing their ships over time, but the new ones are probably similar to existing designs in terms of performance.
Shivans probably use ZPE, or Zero Point energy, that wonderful, renewable energy source.
In a command briefing, Petrarch says that the Kayser is based on Shivan technology, and we all know that the Kayser suppodefly uses ZPE, so that would make sense.

The Shivan fighter weapons are all crap in the game though.

The Lucifer fleet was lost in space for say about 8000 years and they had primitive Shivan technology which wasn't updated for thousonds of years and suddenly emerged in Terran-Vasudan space to demonstrate their power on the weak Terrans and Vasudans.
That certainly makes sense to me. The Shivan fleets do not necessarily have to keep in contact with each other, and the Great War fleet was probably different from the FS2 one due to it emerging from completely different locations.

It is possible that they all have the same roots but broke off either into different battle groups with the same objective, or autonomous factions, each with their own agendas. This would explain why the Lucifer fleet and the Sathanas fleet both used some of the same technologies, but the Sathanas fleet might have progressed in some ways and added new stuff in.

I really don't think that they have some guy sitting at a desk with a flipbook of known designs identifying ships as they come into radar range...
A computer is probably used for that type of stuff; it has probably been given a big list of existing ships and possible names. When a ship comes in, it checks to see whether the ship is new or one that was previously encountered. If it is a new one, the computer assigns it a new name, which command tells you.
