I think I responded to your issue on GitHub about this – just want to add that recording to Hap may not be the best idea, if you can avoid it, because Hap is not particularly fast to encode so you will usually drop frames. If your workflow allows it, you’ll probably get better results by recording to an intermediate format and then transcode to Hap afterwards.
I definitely see the use of more options for controlling Syphon Recorder – might think about adding AppleScript and/or OSC controls in a future version.