Yeah, modding this game is a very good way to learn what you want to add to your own game. Every time you hit another modkit limitation... yeah... we could do that better.
i'm not a modder so excuse me if this is dumb. how much control over the trees changing with the seasons do you have? could you piggyback a sound onto the changes in the trees? in otherwords as the trees bud you get 1 set of sounds,and then as it leafs you get another?? the crops is about the only thing in game that is close to 4 seasons<plant,grow,harvest,winter> and i bet we have very limited control that way. just trying to think of a workaround. sometimes thinking outside the box helps.