Central banks have an impossible job because the currency is in an unstable equilibrium. If prices go down then people hurry to sell and put off purchases, making deflation worse. If prices go up then people postpone selling and bring forward purchases, making inflation worse. If you can keep inflation at 2-3 % then that works pretty well, but it is an impossible job when there is any shock to the system, like a war or pandemic or changing your whole energy infrastructure.
PLAN B: (1) Instead of inflation, attack the problem quickly and directly by allowing the Central Bank to tax cash holdings in banks -- presumably by 2-3 %/year, but they can quickly put it up and down, and it can even go negative. This needs to be combined with having an expiry date on physical notes. This is meant to be only a medium of exchange, not a store of value.
(2) Establish a secure inflation-proof place for people to put their money that doesn't require them to know about investing. It should be a currency that is backed by physical stuff. What stuff? The stuff the economy will need to keep going in an emergency: PPE, diesel, ammunition, raw materials for industry, food stockpiles,... This is meant to be a store of value, not used as a medium of exchange, so it can't be given to others, only changed into the medium of exchange currency. When there is a reduction in the amount of this currency then the central bank has to reduce the backing assets by selling them.
There needs to be easy conversion between the 2 currencies. The rate will be set by market forces, but the central bank's job will be to try to keep the two from diverging too fast.
