Thanks a lot for playing and for the detailed notes!
You were right about the season label: the header switched to the next season while the harvest card still described the one you had just finished. In 0.2.2 (now live on the page) it reads "season N harvested" until you press "Next season". I also added your suggestion to the level 3 hint: it now points to "Forecast shade" to preview where the sunflower's shadow will fall.
If anyone else tries it: I'm still curious which mode you'd keep playing — Puzzles or Seasons — and what would make a full version worth it.