I see how that's frustrating. But I also see how you've been enthusiastically telling a very dramatic story full of dramatic rises and falls (and narrow, hard-fought victories), and said that you've "cracked" the game but this new mode gave you a whole new system to try and figure out, so... I don't feel that bad? It sounds like you kind of, in spite of yourself, had a pretty OK time? Or at least came out with a pretty dramatic story. I have one where in a massive game of <COMPETITOR'S GAME> I ended up changing royal succession laws and saw my empire just fall to pieces in a generation because of some part of the law that I forgot that allowed a distant relative to inherit half the kingdom. It ended the game and I "lost," but I loved the drama in the story.
The main system for advancing Era score here is via technologies and civics. Unlike the Dedications, there's no real difference between how you get score in a Golden age vs a Dark age, but the threshold is way lower in a Dark age (correct me if I'm wrong; I'm not the dev on this). So you can't count on Dedications, although defeating a barbarian camp, adopting a new tier of government, converting a holy city, etc., is always a good bet.