[PvK]

Welcome Barryg!

The Empire Type you mention doesn't actually have any effect except on the word that is displayed for the second part of the empire name.

For example, what you are specifically asking for with DATA/EmpireTypes, is to be able to change the name of, say, Klingon Empire, to Klingon Pansy-Picnic, which would have no effect (except maybe to inspire attacks from other human players).

SJ's suggestion of Culture type is actually just a set of modifiers to abilities, which would not affect the AI much if at all.

What it seems to me you are really asking for, is the ability to change the AI settings during play. This IS possible, for advanced users, by saving the game, modding the AI files, and then re-loading the game. In fact, this is a common and very effective way to tweak the AI, observing what it is doing, and micro-managing adjustments so that it does what you want. It's a tedious and complex process, but rather fun and rewarding if one has the time to invest.

PvK