For anyone looking to export highlights of an ebook off a Kobo E-reader, here's an easy way:
After you've plugged your Kobo into your computer and can see the Kobo drive, there should be a file called Kobo eReader.config. It’s located on the Kobo drive in the ".kobo" folder inside the "Kobo" folder.
Right-click on the Kobo
eReader.configfile and choose to open it with a basic text-editing program like Notepad.
Add the following code to the file at the bottom, or anywhere as long as it’s separate from the other code:
Safely eject your Kobo ereader from the computer.
With this, the long press menu of a book will have an extra option, "Export highlights". Using this will prompt you for a file name and export the annotations to that file in the root directory of the device.
I have a Kobo Clara HD (highly recommend) and can confirm this works like a charm.