Hi. So on on my custom game mode server I have random starting season, season lengths set to short for all seasons (which should be 15/12 days), and tuning adjustment for the length of a short season (where I changed it to 12/10 days). When I'm starting in Winter, Winter has only 6 days. If I push the winter event it goes back to 10 days.
Generating a world with non-default season lengths