I found that all the buildable items like buildings, advancements and units have a so-called strategy-score.
This score, depending on the nature of the item, is split up in several sub-categories.
But if all of these sub-categories are added together, the score would eventually be "1.0" for almost everything.
There, however, was one exception: The advancement to be able to water your units.
I figured that was because being able to do so was really important.
So what I did was going through all of those buildable-items-files and tweak the scores in a way to make the AI emphasize certain things over others.
I increased the values for most buildings and advancements so the AI would foucs more on its infrastructure.
This prevents them from massively falling behind in city-development in the later stages of the game, where some of the buildings really have massive impacts on the cities performance.
I also decreased the values of earlier weapons, armors and units compared to the values of later weapons, armors and units.
This makes the AI actually use the more modern and powerful designs instead of still just building very basic soldiers even in the third era.
This saves them a lot of credits in supply-costs and prevents them from losing whole armies to things like orbital bombardement.
A consequence is, that the AI will be slightly less agressive early on because it builds fewer units.
In the later stages of the game, however, it is much tougher to compete than it was without the mod.
First of all the AI will not start to fall behind in production and tech since it will have built all the usefull buildings.
And secondly: Facing Rank 15 units with 100+ Power is much scarier than facing a stack of puny Rank 1 infantry, where the individuals have like 4 Power and that die to 2-3 Orbital Bombs.