So i closed Reaper and then deleted these 2 files in Reaper resources folder:
reaper-auplugins64-bc.ini
reaper-auplugins64.ini
I opened Reaper and now the Audio Units
are seen in Reaper, but only the x86 AU versions, not the x64 versions.
Sighhh ...
EDIT: I have found a solution, it's written in my first post, at the bottom.