If you have a swiss pass or swiss half fare pass can it be used on the Golden Pass train between Montreux and Interlaken ost. Is the Eurocities train 2128 between Montreux and Zweismmen the "Golden Pass Train"
The Swiss Travel Pass (a Swiss Pass is for Swiss citizens) and the Swiss Half Fare Card both cover all trains on the Golden Pass line. There are a few types of trains (no EuroCity though), but they all follow the same route. The train you mentioned is called the "Golden Pass Panoramic" train.
Please see our Golden Pass page and the downloadable timetable for further details.