It is hardly German exceptionalism to want to enforce its own constitution. However Germany has also ceded sovereignty to the EU in a large number of areas.  When there is a dispute over EU competency or actions, the EJC is the final arbiter. What would concern me is if the German Court arrogates to itself a right to adjudicate on EU actions which effect many member states.  Even the House of Commons doesn't claim jurisdiction over EU affairs.

notes from no w here