I'd like to suggest a few general principles. First open source usability can be as good or better than proprietary commercial software. One of the reasons that first attracted me to Moodle was I found it much more usable than the commercial product used where I worked. Bad UI design is not the preserve of FLOSS software.
Then I discovered the Moodle Cloze question type and decided that there were some usability issues to address. The problem was not that it is hard to do exactly what you want, but it is fairly hard to do anything unless you are prepared concentrate and think hard about learning the syntax.
This brings me to a second general principle which is taken from the title of a book on interface design. "Don't make me think”. People who use software want to solve their problems, most have no interest at all in learning software. Software should make it easy to do the most commonly performed tasks. By the time people have done that they are often interested and committed enough to use the more complex features.