I'm sorry you feel this way, but I'd appreciate it if you refrained from personal attacks. If a reconciliation was performed monthly, these missing transactions should be spotted as this is the whole purpose of reconciling bank accounts. I understand the complexity with multicurrency, fees and FX differences. However, this should not prevent you from spotting missing transactions.
As previously stated, it is unusual for one bank account to handle multiple currencies, even with PayPal, for multi currency, the are recorded under separate accounts. Therefore, it would be conventional to set up separate accounts for different currencies.