The CSU should take its election manifesto to its logical conclusion

From today's Open Europe news summary:

Die Welt reports that according to a draft copy of the CSU’s European election manifesto, the party wants to establish a new ‘EU competences court’ staffed by national constitutional judges who would ensure that the EU does not legislate in areas which cannot be equally well or better dealt with at the national or local level.
Welt

The CSU should take this manifesto to its logical conclusion and recommend withdrawal from the EU while cooperating with other nations where there is a common interest.  Why give prior authorization to a supra-national body to rule for Germany and then try to limit its scope?  This makes no sense.  Germany is a sovereign country, as are all the other members of the EU.  There is no reason to hand over sovereignty and then beg to get it back.