I managed to write some FFGL plugins for Resolume quite a long time ago, but the thing never worked to full satisfaction. The attempts (more or less successful) are mentioned in older threads in this forum. I can give you the source code if you can't find them here and you are willing to play with it.
A few people tried to fix the bugs in the addon but as far as I know nobody managed to solve them. Nevertheless the code I hacked together worked well enough to be used in some real-life big show, so may be you could give it a try. It used to work with OF0.8.x, so may be it should be updated for newer versions.
And, well, it doesn't work with the latest Arena 6 because now the plugins must be 64 bits.
The whole stuff would need some brave spirit willing to rewrite the ofxFFGL addons from scratch!