@doubleshuffle: AFAIK, Kobos support ePub3 books and will automatically select the NetFront ACCESS engine, if the file extension is changed to kepub.epub.
I converted my test book to epub3 with the Sigil epub3 plugin and it looks OK in ADE 1.7-4.5 and Sigil.
Try changing the file extension to kepub.epub and test the file on your reader.
For those who want to test my file on other readers, have a look at the attached screenshot for the expected rendering.
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