@Doobox and Rob, thanks so much for reminding me of that!
This is what it showed:
There was nothing there. So I moved them all from one of the other locations manually, in the Finder, with RW not launched.
Of course when I launched it, it asked for my licence, which I take as a good sign… comprehensive set of files being put back in the right place.
As a matter of fact, this is the second time this has happened. Oddly, the first time was on an entirely different machine (at work), and then I had to re-install before RW would consistently find the Add-ons.
I put that down to the fact that the ‘Copy Addons from RW 6’ at first installation of RW 7 had failed - it took over 45 minutes, the progress bar kept hanging (that, too, is a clean machine).
For almost three weeks this machine has been stable in this respect; I did nothing in the Finder to this folder; I had no crashes; I was barely using RW; overnight (which really means from the last/previous launch to this morning’s launch) - I am 100% sure - All the Addons moved!
Is there documentation anywhere to suggest which is the accepted/‘correct’/default location for all Addons?