The Torah never refers explicitly to Shavuos or Rosh Hashana by their primary themes of the Torah and the day of judgement. Why does the Torah overlook this?

The Kli Yakar explains that the themes transcend a particular moment.

Torah each day is a new experience, bringing fresh understanding and enhanced insights with it. The Torah is on offer every day, and we choose through our actions whether to accept or decline. Calling Shavuos “Torah Day” is a disservice to our responsibilities.

Likewise, is described as the day to blow the Shofar, because our actions are under scrutiny every day. We are accountable always. Calling Rosh HaShana “Judgment Day” is a disservice to our accountability.