I missed this issue completely but thanks to this voxeu article woke upto it. I mean EZ crisis is one crazy event and events around the crisis keep making you pull your hair once in a while. Germans did not like the support being given to peripheries and there were court cases against EFSF etc. But those cases were mostly by German econs (as far as I can recollect).
It now seems Bundesbank (which is a ECB member and biggest ECB shareholder) has filed a case in German court against Outright Monetary Transactions: