If you want to use the start year for new generated maps, look for "Init" in gamescript: Game Script
I'm not sure how that helps me. Perhaps I'm not understanding.
The current game year can be found from game.interface.getGameTime().date.year when the game is running, but from my testing during map generation game exists but game.interface does not.
Could someone smarter than me show me a simple code sample that would detect a new map being generated (lack of game.interface may suffice for this) and output the year the game is starting in
print("New game generating, starting year = " .. newMapStartYear)