As I have said: introducing joint new borrowing or communitising existing debt by issuing Eurobonds, which are currently being so widely discussed, would not be at all necessary in this context.
It also explicitly states the aim of fostering competitiveness and economic convergence. At the same time, any attempt to set up an intergovernmental decision-making structure to manage a federal sub-budget is likely to be difficult to implement in practice, and the effectiveness of a financial transaction tax as the central source of funding is overrated.