Problem is - there doens't appear to be a new XML file & the file structure User/Library/Application support/Abobe/Bridge CS6 doesn't appear to exist.
I think there is no new xml file because bridge create one if he need one.
If you give new keyword to a picture, i think bridge will create this file. You can try this.
But i think the only thing you'll have to do is just copy your saved files in the same directory even if there is no correspondant files, just copy it and i believe that you're keywords will come back to your new install of adobe bridge.
I have allready done that whith my windows computer, and it was ok
sorry i don't speak english very well.
1. import keywords (but I can't seem to import an XMLfile using the import function)
This option only works on a text file, usually the keyword list that was first exported using the same menu as import (little menu icon top right of the keyword panel)
2. replace the newly created Adobe Bridge Keywords.xml file with the old one...
I agree with guewen on this one.