Works, but I need some help with age transition. I followed your description and set antiquity age to 1, but which value makes the next age accept the end-limit of antiquity? By the end I was at 6/6, but upon entering exploration age, it reverted to 4, so i was 6/4 with some trouble ahead.
I also don´t want to give the AI some free limit up to 6, so it would be nice to only allow the limit they previously reached in the age before.
There should not be changes how the last ages settlement bonuses carry over compared to default game. I had game where I had +2 (6 total with modded limit of 4) for exploration start because of selections of legacies and stuff.