What safeguards prevent a bank from artificially creating balances or simulating deposits, similar to how Bitcoin uses proof-of-work and an auditable ledger?

Ledger Entries.

Every debit and/or credit that a bank does, is entered into the ledger system. The ledger is a double-entry system.

So, let us take 3 scenarios:

1. Bank claims to have received US$ 10 Million in cash deposits. At losing time an audit would show a discrepancy with the cash-in-vault and the cash on ledger.
2. Bank claims a wire transfer from ABC Bank was for US$ 10 Million. At the end of the day, the consolidated reports sent to the federal regulator (usually the central bank) would show a discrepancy also. ABC Bank would not be showing any debit on their ledgers reflecting US$ 10 Million.
3. If a Bank tried to manipulate their own ledger system, see the answer here: Faisal Khan's answer to How is money virtualized? What stops a bank from misreporting its funds? What would a new bank need to do in order to be able to accept and hold virtual funds?