In our trip in BO, my wife and I will take train from Wengen-Wilderswil to Schynigge Platte in end of September. If we don't want to take the same train route back to Wengen, is there any hiking trail from Schynigge Platte to Bussalp, where we can take bus to Grindelwald and later return to Wengen?
Or is there any hiking trail from Schynigge Platte to Lutschental or Schwendi, where we can take train to Grindelwald or return to Wengen via this route?
I have no personal knowledge on that point. This may help. Check this link to Switzerland Mobility. A very useful site.
Expand the map until you can see Bussalp.
Note that if you descend from Schynige Platte to the valley floor, you have an approximately 1600 meter descent. I hope your knees are in good condition. ;-)