You are using Robofab for

In reply to Kerning Macro, Fontlab API:

You are using Robofab for your macro, so you’d want to look at the Robofab docs rather than the FontLab API: http://www.robofab.org/objects/kerning.html

I’m not sure if Robofab handles MultipleMaster VFBs.

Another solution would be to simply put C, G, Q, Πetc. in the right side kerning class for O ;)