They haven't solved why Satoshi chose these unusual ranges [0 - 9] and [19 - 58] instead of [0 - 255]. They have only theories ... eg. lots of computers with these specific numbers .
... you first create a private key, then compute the public key, and then mine blocks. You cannot first mine a block and then change your private key.
That's exactly what could have happened. Satoshi first generated (created) lots of private keys and mined the blocks with the info on the private key, so we have these strange Nonces and extraNonces and time deltas... just a theory