I think this over-capacious usage of the term 'sovereignty' (in this case by Draghi, but it's endemic in contemporary political discourse) is part of the problem, not the solution. ecb.europa.eu/press/key/date…
'True sovereignty is reflected not in the power of making laws'... well fine, except that in a tradition dating back 400 years, sovereignty has been identified precisely as the power to make law (Bodin, Hobbes, Rousseau).
I'm not saying that is the only way to define sovereignty. There are other theories: using Weber's 'monopoly of legitimate violence' or that creep Schmitt's 'power to declare a state of exception'.
But to define sovereignty in terms of the ability to control outcomes is not a theory of sovereignty at all, as it fails to distinguish between sovereignty and the broader concept of power.
If you think sovereignty is a defining attribute of states (what would its point be if it wasn't?), identifying it with a general power to control outcomes has unfortunate consequences. Less powerful states would be less sovereign: are they really states at all?
FWIW I think it is possible to give an account of European integration & its legitimacy without stretching the concept of sovereignty to the point where it becomes conceptually useless.
Not entirely a fiction, though certainly a construction. But a much thinner concept than the contemporary discourse would lead you to believe (which doesn't mean it's not important).