I believe the mistake is to think one can design a reserve currency. The dollar is the world's first reserve currency only because the Bretton Woods monetary system defined it as redeemable for 1/35 ounce of gold after World War II. When the Fed defaulted on its gold obligations in 1971, the world got a reserve "currency" -- before the world reserve asset was gold.

I don't think any government can create an irredeemable credit instrument and have it accepted as reserve currency. Even the dollar as reserve currency had to come in the back door.