As you know, Resolume changed to FreeframeGL 2.0 a while back, so plugins built for FreeframeGL 1.6 are no longer compatible.
The SpoutController plugin is complicated, so conversion is not simple. However, I have made a replacement and it seems to work OK.
Apart from the change to FreeframeGL 2.0, Resolume no longer finds plugins in sub-folders and this requires changes to where the various files are located. This is in the update documentation. If you can get the SpoutBox example working, you should be able to do the same with the sketch you refer to.