"if the CFAR staff had put high probability on having success on one of those three fronts, then I think that logic is worth discussing."

It would seem somewhat strange for CFAR to test three variables they did not expect to increase...

Also I do not think happiness is very hard to adjust. There is research that some simple things can improve your happiness and have been tested with RCT's. E.g. meditation and gratitude lists had a measurable effect.