What I wonder is what could happen if any of the officials, or even politicians, with managerial responsibility for that action, happened to visit Luxembourg. Because they, surely, were involved in the commission of a crime in Luxembourg. Think how lovely it would be to see them jailed.
Not that that would be an unqualified good thing. Because to the Germans, the bank itself was, arguably deliberately, assisting the Germans on the list in committing a crime in Germany – of evading taxes.
If either government took the approach of the US to the scope of its jurisdiction, both German tax officers and Luxembourg bankers would have to be very cautious with their travel plans.
Probably how it stands is that each holds the power in reserve, to retaliate if the other starts by arresting important people. That would be for the best, attractive as the idea of German tax-collectors in a Luxembourg jail is.