I probably agree that "I'm working on decision optimization" conveys more information in that case than "I'm working on rationality" but I suspect that neither is really what I'd want to say in a similar situation... I'd probably say instead that "I'm working on making more consistent probability estimates," or "I'm working on updating my beliefs based on contradictory evidence rather than rejecting it," or whatever it was. (Conversely, if I didn't know what I was working on more specifically, I would question how I knew I was working on it.)