I just found a new built of Gimp 2.8.18 for Mac users with
recent gmic plugin 1.7.9 under GimponOSX:http://gimp.lisanet.de/Website/Download.html
! It is not written in the news page of GimponOSX, still for Mac users with Sierra installed there is a (long awaited) update.
Using this built, you have to delete the gmic plugin possibly copied to "~/Library/Application Support/GIMP/2.8/plug-ins/". Actually my plugin built is linked against the older Gimp (2.8.14) from GimponOSX and will crash because of library version mismatch!