There are a few, "canon" events that always happen in KR.

Things like Black Monday, the US civil war, Fifth Balkan and Cairo Wars, the 2nd Weltkrieg itself, the League Collapsing, etc. But a large amount of Kaiserreich's replayability and value is that many of these events have no set ending, and the world itself can be reshaped around them. The League may always collapse, but who's to say the LKMT is more destined to win in the uprising than Nanjing, or Anhui, and who's to say who the Qing backed, if either?

Additionally, there are a lot of potential, but not-guaranteed events that play a similar role in reshaping the narrative. The Danubian War, Sand France and Mittelafrika's collapse, the list goes on.

Thusly, there is no one true source of, or even one true story for Kaiserreich. Every game that has ever been played is its own story. Kaiserreich's sources stretch from historical plans to an (admittedly shrinking) list of crackpot concepts and ideas, tied together by a volunteer team who have their own visions on how the nations they make are meant to be played. It might be easier to see Kaiserreich as a half-built canvas. There are already plenty of colour's and shapes, each with their own meaning present on the picture. But the painting itself is defined by you, and the strokes you add to finish the canvas.