Well, I wasn't trying to cover every type of fiction. I think we'd have to distinguish between money as a system of exchange and the stories we tell about the value of money.
So money itself would fit under the category of techniques or instruments that are used to achieve a purpose. The purpose would be largely fictional even if the extent to which the means achieves it can be objectively assessed.
So if the point of money is to enable the trade of goods with utmost efficiency, and the point of trading is to earn a living to enable us to have a fulfilling life, it would be an empirical question how well money serves that end.
Money makes some people happier than others and this system may be more or less self-destructive. In any case, the value-based goals of happiness, prosperity, and so forth would be driven more by fictions than by empirical facts.