Swiss/German itinerary - is it reasonable

Sounds basically OK.

Day 1 Geneva
Day 1 night Travel to Bern
Day 2 Bern (stay in Bern)

Does this mean you are arriving in Geneva and going on to Bern the same day?
Depending on what time you arrive, and how tired you are, you may want to spend a few hours looking round Geneva, first night in Geneva and go on to Bern the next morning.
Geneva ("Genève, Cornavin" station) to Bern takes 1 hour 50 minutes.

Don't bother with a night in Interlaken, go direct to Mürren and stay the extra night there.
Bern to Interlaken is 55 minutes, Interlaken ("Interlaken Ost" station) to Mürren is 50 minutes, so you have plenty of time to spend a few hours in Interlaken en route.

Mürren to Baden-Baden is 4¾ hours by train, change at Lauterbrunnen, Interlaken Ost and Basel SBB.
Baden-Baden to St. Goar is about 3 hours.
St. Goar to Amsterdam is about 5 hours.

Hi, can you explain if you will be continuing your trip for several days at Amsterdam? Otherwise, I would recommend flying out of Frankfurt instead of ending your trip with hours of train travel. St. Goar to Frankfurt airport is ~2 hours by train.

Yes, we are flying out of Amsterdam after spending three days in Amsterdam. I have 2.5 days to get from murren to Amsterdam and need advice on what is best to visit along the way or the route that will provide the best sites to visit. This part of the itinerary can be changed based on feedback that I get.

I would skip Bern, and spend the extra time in Geneva (or Lausanne) and Mürren. Although the weather needs to be considered.

I recommend spending the first night in Lausanne or even better Montreux. From Montreux you can easily take the Goldenpass train to Interlaken. Then train to Lauterbrunnen and cable car to Murren. All of this runs very smoothly on the excellent Swiss train system. Skip Bern and spend 3 nights in Murren. You will love it!

Thank you all for your advice, it is greatly appreciated

Avtar