Hugo, thanks for your feedback on the documentation. We only make major changes to the documentation when we release a new version.
We don't have plans (nor resources) to document every protected method. However, we do try to document classes and methods as needed to enable users to extend the API for specific use cases. For example, symbols, renderers, layers and tasks. If there are specific additional use cases, we can help explain here on the forum as well as update the documentation if it seems to be a common use case.
Again, big thanks to everyone who gives us feedback on our documentation and API 🙂