In the latest update you can import the Ack No.,Ack Date & QR Code into Posted Sales Invoices & Posted Sales Credit Memo using the new feature avaliable out of the box - Import E-Invoice Details.
When you click the Import E-Invoice Details a dialog box opens, you can select multiple JSON file to be imported.
Once import the data is updated in Sales Invoice Header & Sales Cr. Memo Header, below image for reference purpose.
In this way you can update the E-invoice details inot dynamics nav.