The Adobe ePub version I sideloaded does have endnote linking capability afterall. The problem is that it is a bit flaky. One time a press on the link doesn't work but does turn the page. The next time it might work, but it always takes about 10 seconds to retrieve the endnote. That is unacceptable of course.

I notice that clicking an endnote link in the kePub will retrieve the endnote more quickly, but it also invokes the Kobo syncing mechanism which slows everything down. While the Kobo is phoning home to tell the mothership I just went to an endnote, some screen touches don't seem to work. Only after the syncing icon in the upperleft screen disappears can I press Back to return to the page whence I came. That too is unacceptable as it will take up way too much time.