For what it's worth: a while ago I programmed a crude cloze editor in JavaScript. You can find it here: https://sites.google.com/site/moodleclozecreator/
It allows importing and editing existing cloze code and it can also export normal text with _________ instead of Moodle cloze code. I wish there were a way to add HTML formatting, e.g. using TinyMCE, but I'm not sure how to do it, partly because I don't understand my own code anymore