I looked up your recommended train route from Lauterbrunnen to Hallstatt, and am worried whether the allotted 6 min transfer time at Interlaken Ost is enough time to make it to the Bern train?
Interlaken Ost is a small station, and connecting trains are often placed on opposite sides of the same platform-- taking you all of ten seconds to change trains. If you have to go down stairs and up to another platform, it will only take you two minutes. Swiss trains are extremely punctual, so no need to worry about a late arrival.
Will is absolutely right. Here's a link to the Interlaken Ost station map, which will give you a good idea of the size and layout: http://www.sbb.ch/content/dam/infrastruktur/trafimage/bahnhofplaene/plan-interlaken-ost-plakat.pdf It's really a very small station. And if a Swiss train is more than 10 seconds late I'd be shocked! Good luck,
Gary
I either had the same route heading to Bern or a similar one If memory serves we had a couple of choices and went from Lauterbruunen to Ost pn earlier train. As described, I watched people calmly exit later train and get on one I had arrived early to catch.