This is how to update the document status in Microsoft Dynamics 365 Business Central from the eversign portal, from the Sales Order List page.
From the Sales Order list page, select Actions > Astral eversign
Figure 1 | Sales Order List
You can see above that you can either update a single document, with action Update Selected Doc. Status. Or, you can update all Sales Order documents in Status sent using the action Update Doc. Status for ALL Sent.
You can see the status on the list on the additional field, Astral eversign Doc. Status.