It turns out the GA C2 plugin does work with Cocoon after all!!! While I was testing they were having technical difficulties with data processing or something (they put an announcement up), so there are longer than usual delays of several hours for stats to be shown in the 'live feed'. But when I got up this morning I can see all the stats from my tests yesterday.
So happily I can confirm that GA C2 plugin works with Cocoon :
Hey Artpunk what plugin did you use in Cocoon when compiling? I can't install the "cordova-plugin-gameanalytics" plugin. Cocoon throws an error saying “Uh oh!
“....cordova-plugin-gameanalytics/GameAnalyticsCordova.m” already exists!” when I add it.