> In the future, I also want to implement some kind of plugin system because certain subjects require a different learning style. But I'm not sure yet how this would work. I need to think about it.

Right. People say that HelloChinese is better for Chinese because some of the question types are drawing Hanzi, so I think this is a perfect use case for a plugin system where a course could add a plugin for Hanzi/Kanji drawing and not be slowed down by the core developers.