First - to clear up some comments from the last post, particularly in the Emmental.
<<"1. 8th / 9th - 11th Sept Arrive in Zurich, (most likely on 8th). Upon arrival to head to Wengen (Zurich Flughafen- Bern-Spiez-InterlakenOst - Lauterburnnen - Wengen) (to follow kim's guidance pg6 Part 2) - should take about 3 hours. I've emailed to Hotel Bellevue, Wengen to inquire about the room availability for those dates. I'd prefer to do the Leuterbrunnen to Stechelberg hike as mentioned on Kim's document on Pg 19 Part 2. Could also tick the box from Leuterbrunnen to Wilderswil. Would you recommend Schynige Platte to First? Could these be done in one day? If so, then I could also leave on the 10th instead of 11th.">>
Definitely not in one day, and , as noted, I'd suggest Männlichen to Kleine Scheidegg instead of the Schynige-Platte to First hike.
There are plenty other things to do in the area, which is perhaps the most impressive alpine area in Switzerland, whether you arrive Zürich on the 8th or the 9th, and recognizing jet-lag, I 'd stay through the morning of the 11th.
The Bellevue will pick you up from and take you to station, so an 0803 departure is possible. The whole day could work with an 0903 departure, but it would almost surely require stashing your luggage at the Show Dairy. You may miss breakfast at the hotel, or may not. They might make you something to take with you to eat for the AM.
Assume 0803. Go to Sumiswald-Grünen Bahnhof. The name distinction is sometimes used for bus vs. train, at the same station. The Sumiswald-Grünen is the train station, and S-G-Bahhof makes it clear that the bus is stopping at the train station. They are the same place.
The routing is through Thun, as you noted, and the fastest route is through Hasle Rüegsau and on to Affoltern i,. E, Dorf, by bus at 1114.
That works if you can stash your luggage at the show dairy while you have lunch and perhaps walk around the area bit.
I'd e-mail the dairy and ask if it possible. They have a lot of space, so they might well allow you to do that.
Afterward, bus to Affoltern-Weier, and bus to Sumiswald Post. Walk 5 minutes to the Gashof Bären. Have a tea, or coffee. Dump your bags, bus to Trachselwakd, look around, return afterwards to Sumiswald. By bus, or part bus and part walk if you are energetic. I know that all that works, without even fine-tuning with the time table. Beware the mid-day gap in the buses through Trachselwald.
Look around Sumiswald...not much special in my opinion...have dinner at the Bären.
If you have to leave luggage at Sumiswald or nearby, the first thought would be to go all the way to the Bären from Wengen, than back to the dairy for a cheesy lunch. Have to look at schedules, but, it is certainly possible.
As you noted, you can get to S-G station at 1139. Bus up the hill at 1144 to Sumi- Post. 5 minutes walk (150 meters) to hotel. Check in, dump bags. Walk back to Post by 1215.
Catch 1216 bus to Aff-W. from Sumi-Post. arrive at 1223. Change. Catch 1237 bus to Affoltern Dorf at 1239. Walk a couple of minutes to the dairy, have lunch.
Catch 1414 bus to Aff-Wei at 1419, change for Sumiswald-Grünen at 1433 arr S-G Bahnhof at 1442. Oooops - Bus to Trachselwald not until 1634. Midday break.
So, walk 1.2 km to Trachselwald. Arrive 1505 to 1515.
Bus back to Sumiswald Post at 1721. arr. 1727 Earlier is possible.
Walk to Bären, have dinner.
There is be some slack in that ....Certainly you could have dinner later than 1730.
I'll not try to fit in Trub or Trubschacen. Too complex. Can only be done by skipping lunch at the show dair or dinner ate Bären. If you decide that you want to do it, play with the timetables. You coud saty a the Hirschen Langnau. Nice place.
You have a good grasp of the bus and train schedules, so you can certainly rearrange things. My objective was to get you by a possible route from Wengen, to the Show Dairy in Affoltern i. E for lunch, an Emmental village, and a famous Emmental inn..
I think your Luzern/Sachseln plans make sense, but I have run out of time and will have to revierw them later.
I'll reply to your latest post tonight or tomorrow, more likely. Perhaps others have comments.