Leaving aside the basic definitional stuff (the difference between private banks and central banks is normally considered to be state authority), why does anybody want to accept the money from your "central bank" as payment?

With real central banks the answer is "because creditors in a particular state are legally required to accept it as payment for debt, and everyone else in that state needs it to pay taxes which are owed whether there's money in their account or not". With yours, it's the opposite: if I accept your coins as payment you tax that payment for my work/goods out of my account and if I don't, you give coins to me for nothing. (And I can still earn in other currencies without owing your "tax", just as I always have done)