We have replaced our SharePoint add-in with Microsoft's recommended integration approach which allows access to OneDrive and all SharePoint sites without the need to install anything.
For details, please refer to our support article: Import a document to Simul
To import a document from SharePoint, the Simul Documents app must be installed on your SharePoint site. Once installed, navigate to the document library or folder and select the Microsoft Word Document you want to import:
You can then either select “Open in Simul” from the ribbon or the document’s context menu shown in the following two screenshots:
You will see the normal SharePoint “Working on it…” message as the document is transferred to Simul. Once complete you will be redirected to the new document in Simul and can edit the document as described here: Editing a document
Every change you make within Simul is recorded as per usual. If changes are made to the document in SharePoint, the next time a user selects "Open in Simul" a new branch will be like so: