Our Integrations are passive, i.e. they wait for a message to come in and transfer it. Because we do not store the data of our customers, we unfortunately do not have a way to restore or import any historical data.
Our recommendation to import any Transactions that existed before your Integration was installed would be to contact Sisu and provide a CSV file of Closed (pre-Real Synch) Transactions. Sisu can them perform a file import for those Closed Transactions.