If SyphonNameBoundClient is not working you ought to double check you are passing both the appName and the serverName correctly with the correct case. All implementations of QC and FFGL and Jitter uses the same class with no issues.
As far as GL_TEXTURE_2D, Syphon will *never* be able to output those. You will have to render into your own FBO with a 2D texture attachment to “change” the texture target. Sorry, this is a current limitation of the underlaying API (IOSurface).