5 Minute Train Transfer Window

This is very typical with Swiss Rail. The trains run like clockwork, it will be very easy to make the connection. If your train is a little bit late the connecting trains will wait a few minutes for any latecomers. If you do manage to miss your train to Interlaken, there are direct trains every 30 minutes or so. Since domestic Swiss trains don't require reservations your ticket from Basel to Interlaken is valid for any departure.

That puts my worries to rest. Thank you!

If you know the platform numbers you can make "dry runs" on this map:

http://mct.sbb.ch/mct/infra_services-uebersicht-bahnhofplaene-basel-sbb-a4.pdf

For Germany, the Bahn website lists track numbers for most trains, but I've never found that information for trains outside of Germany.

Look in the coach. Often major trains have paper schedules distributed on the seats with that trains route and connecting trains at each station, with track numbers. Or ask the conductor.

The main thing is to be prepared to get off when the train stops. Beforehand, move with your luggage to the end of the car by the door. Get off when the train stops. If you still don't know the next platform, look for a station schedule on the platform, then proceed to the connecting tunnel, bridge, whatever. The stair to each platform will be clearly marked in the tunnel.

The Swiss Rail site does display platform numbers:

http://rail.ch

Then he should not have any problems.

Unfortunately, SBB doesn't show the arrival platform for this train from Paris, but it does show the connecting train leaving on 10, so get off the train and look for platform 10.

Be ready to be first off the train then fly to your connecting train. Even in Switzerland this sounds too close for comfort.