Unfortunately currently there is no way to import the CSV, sorry.
Depending on how much you're comfortable with JSON, you can create local storage database manually. To access the local storage, right-click on the extension icon and select "Inspect Popup". In the popup, click on the "Application" tab on the top. Select "Storage > Local Storage > chrome-extension://..." in the left navigation. You'll see a bunch of keys here. To repopulate notes, you need to modify the "pagenotes" key. You can add a couple of test notes to see the format of this key.
I've been thinking of adding the import feature for some time. I'll expedite it now.
Sorry again for the trouble.