Thanks, sorry for raising your hopes about audacity.cfg but the other person has confirmed also that resetting audacity.cfg does not help.
If you are sill using Yosemite, do Audio Units load in GarageBand or any other audio editor? If not, then I don’t think Audacity needs to be concerned. I don’t know what version of GarageBand comes with Yosemite, but here is how to load Audio Units in GarageBand 11: http://support.apple.com/kb/PH1987 .
Are you sure it wasn’t an error about Critical Nyquist Files, due to running Audacity from the DMG:
Installation: Do NOT run Audacity from the DMG!!!! ?
Gale