BobFrmAust Are they able to be used on regional and sightseeing train around the Interlaken area? Or is a Swiss Pass of some duration advisable?
Around Interlaken the pass is valid on the main railways: To Grindelwald, Lauterbrunnen, Wengen and Murren, and to eg. Luzern. For mountain railways you get 50 or 25% reduction depending on the railway. Just inquire when you are here.
I have been unable to reserve seats on Swiss Rail via the Eurail App but have booked them via Swiss Rail … is this the norm?
The norm is not to bother with reserving seats in Switzerland. Trains are mass transit. You just must make sure your pass is active, and then you can travel at will.