juce has supported audiocomponent entry point for a long time. I’ve noticed some odd behaviour with au validation & apple products on 10.13 to do with this though, so it might be worth checking.
I tested all our JUCE plugins after doing an update install (without erasing my drive) and a clean install (first erasing my drive). Both work fine, however I may have ran into some macOS bugs when doing the clean install. Skype and Reaper wouldn’t install, but after I restarted (where there was a really weird turquoise screen before it restarted) those programs installed fine. Could have an effect on AU plugins showing up too perhaps, as shown in that Reaper forum thread.
We have yet to see regression in support of some API (mind the yet )
One product is actually hosting AUs (using in-house code not JUCE) to allow 32-bit wrapped to 64-bit using IPC.
So far even very old plug-ins show-up and works from my tests under Logic X.
The only quirk was with plug-ins (also new ones compliant to latest standards) not showing or scanning until I restart my machine.
Even clearing caches simply made auval+LogicX scan the plug-ins that were already showing up and still ignoring the ones I’ve just installed.