Chutney makes clear what Chutney (I'd use a pronoun, but I don't know what gender the writer is) is missing, and that doesn't jerk my chain so much.
If I were making a thematic calendar with readings -- with an overlay "sanctorial" calendar of the "saints" and major anniversaries -- I'd start with the procession of the seasons.
After all, the Christian calendar is based on the Jewish calendar, and it has agricultural roots. Seems a good place to start, and then attribute values to the seasons. Values which speak to the particular congregation, if not the UUA in general.
And if a person was going to start compling useful liturgical material, why not go to the prayers of James Martineau? He understood the seasons better than most.