Colmar france to Obertraun Austria

I looked it up on the German railways site (bahn.de). By train, this will take about 10-11 hours.

There isn't really a direct air route either, that won't involve lengthy trips to and from airports. My suggestion, if you don't want to travel all day, is to pick somewhere in Switzerland or Southern Germany to spend the night along the route.

"pick somewhere in Switzerland or Southern Germany"

Or in Austria (Tirol). A lot of routes go from Zurich through the Tirol to Innsbruck and from there via Stainach-Irdning to Obertraun. You could spend a night somewhere in Innsbruck, or east or west of Innsbruck in the Tirol.