On OS X, there are two locations that VST plug-ins are supposed to be located:
/Library/Audio/Plug-Ins/VST/
/Users/XXX/Library/Audio/Plug-Ins/VST/
(where XXX is your user name)
Renoise only offers one location for scanning. For security reasons, i try to manually move all my plugins into my user path, but some plugins won’t work that way. It would be coherent with the OS design if Renoise automatically scanned those two dirs on OS X.
Hmm…
Good idea, personally i haven’t run across a single plug-in that didn’t work from
~/Library/Audio/Plug-Ins/VST/ (I’ve got all my plug-ins there, not a single VST in /Library/Audio…)
Just curious wich plug-ins are causing problems?
Technically it shouldn’t matter in wich Library/Audio/… they are stored ~/ or /
I made another post about default paths for the mac version some time ago.
Forgot VSTs completely 
The proper order seems to be ~/, /Library/, /Network/Library/ and /System/Library/
So yes Renoise should scan the first 2 ~/Library/Audio… and /Library/Audio… for VSTs.
Link to Apple(Look at the bottom).