The central bank doesn't have a crystal ball to know with certainty where inflation will go. Much of that depends on historical events outside the US that are by definition unknowable -- how will food and energy prices be affected by war in Ukraine, for example?
But central banks are able to plan and then adapt appropriately as circumstances change. And citizens have long voted for effective central bank policy -- economic fears about inflation and recession are reliably the #1 popular concern. If a digital currency can help this, most voters will be very happy with it. After all, for people (like myself) who already make 99% of their purchases with credit cards, they're not giving up much.
That government officials are fallible and incompetent is (in my opinion) the weaker argument. Even if they were extremely competent and had a crystal ball that predicted the future (they don't), nobody should trust the intentions or the goals of government agencies with such ubiquitous and unchecked power.
I could be wrong, but I don't think many citizens would vote for a policy that would give up so much of their privacy, autonomy, and civil rights for the hope that central banks and government officials will make the right economic decisions next time given the data a digital currency provides.