Dave's understanding is correct.
The cableway/train from Kriens or Alpnachstad to Pilatus is fully covered by a Swiss Travel Pass in 2017 but this section will return to being discounted 50% from January 1, 2018 (as it was prior to 2017). Discount still requires using a counted travel day on this pass. Other trains, buses, and boats, and museums around Luzern are still fully covered.
Details can change at any time, but most often at the start of each year. These are based on contracts negotiated with the transport operator.