Interesting mod. However I think there should be also drawbacks for each type of the government.
For example, Despotism should have a negative production in non-capital cities, as well Oligarchy the same for gold - they draw the resources from the masses to feed the few, thus this makes the former unhappy, so maybe also a respective happiness bonus and penalty. So, for every gold/production bonus in capital there is a penalty in other cities, as well as happiness, but on a scale 1:2 - this way you can't grow infinitely with such governments without getting problems.
Theocracy should get a science penalty in later eras.
Communism should focus on science instead of military. Plus diplomatic penalties with every exploitation-based economy, like... well, all of them, especially Fascism, because of the fundamental ideological differences.
Fascism the same as Despotism and Oligarchy, but on a bigger scale and some penalties in diplomacy with liberal and communist governments.
IMHO, every decision should weigh out the pros and contras, so you have to consider what you want and what you are willing to sacrifice for it. You want more gold and are willing to sacrifice happiness - choose oligarchy or corporations. You want to go to war - choose despotism or fascism. Want to be a peaceful sucker in your comfy edge of the world - choose democracy, communism or technocracy. But, on the other hand, most of them are just variations for only two forms of socioeconomic formations and unfortunately the game doesn't have the mechanics to implement them proper without fundamentally rewriting it. For example boosting happiness with gold, like in Civ2/3 - would be THE solution for D, O and F - raid your neighbors and be happy, like it was/is IRL. And so on.