Being aware of the JUCE_ARA fork and having discussed it with people at Celemony and SoundRadix we are actively working on closely integrating the ARA SDK into JUCE.
We are hoping for a solution that will fit into the usual JUCE development workflow, and adds ARA capability to hosts and plugins by enabling the ARA format in the Projucer or CMake. The JUCE_ARA fork goes a long way to that on the plugin side already.
ARA enabled plugins however can have a large number of interactions with the host and have to behave correctly in a lot of possible states, and I don’t think even a closer integration can make that go away. So it will still be necessary to have a good mental model of how ARA hosts and plugins interact with each other. There are a lot of assertions in both the ARA libraries and JUCE_ARA codebase, and many of them are there to help enforce that mental model and general understanding of the ARA concept.
That said a minimally viable ARA plugin doesn’t have to require a lot of added code, although it will only utilize a thin slice of all that the API allows. Hopefully tutorials and comments can make writing ARA plugins gradually approachable.