I am impressed. I cannot managed one panel if it's written in German, unless if its Moore's League of Extraordinary Gentlemen, and in that case my German speaking wife is of a great help. When I was a teenager I have self learned a bit of Spanish by reading tons of Spanish Conan comics during holidays.
I am totally with you regarding the prices differences, and luckily my Gaston Box set was a gift to me. I can't believe that there are missing strips also in the German edition. Notice that this edition features the new colouring by Frederic Jannin that follows more closely Franquin's original indications. And yes this is a complete edition, including early Jidehem strips.