"Central bank independence, interpreted fundamentalistically as a prohibition of monetary financing of fiscal policy, is part of the German basic law. "

Avtually no. Part of the european treaties, yes. But the independence of the bundesbank rested on a ordinary law.

>The entire German political establishment appears to agree that the ECB is configured as it should be<

A good part of said establishment now actually thinks that the ECB is misconfigured, Germany only having as much of a vote as the smaller states.