In my opinion, the traditional technologies of issuing money and storing it have compromised themselves, I mean that the US may have debts that will never be paid and a currency with which they can manipulate other countries. And perhaps other countries are considering blockchain precisely for the reason that this technology can ensure that none of the participants will engage in uncontrolled emission, for example.
In addition to Proof of Work, we know such a consensus algorithm as Proof of Stake, and in the case of creating a CBDC, we are probably talking about something similar, there is no need for such a number of nodes as in the Bitcoin network.
Thus, if I understand the problem correctly, states implementing a single currency for mutual settlements using blockchain technology can, in addition to standard legal procedures (intergovernmental agreements and so on) they can secure the emission and circulation of CBDC between each other, including technically.
Fiscal deficits and national debt is a political problem, not a technical one. We don't have a national debt because banks use relational databases to store bank accounts. Blockchain not only won't help this problem, it has nothing whatsoever to do with it.
And a CBDC--no matter how it's implemented technically--will not change the value of the currency that is being digitized.
A CBDC is just a digital form of an existing sovereign currency. It doesn't solve any broader problems than making it so people don't have to carry around physical paper cash and metal coins.