First off, I think your observations about terminal values are spot-on, and I was always confused by how little we actually talk about these queer entities known as terminal values.

This discussion reminds me a bit of Scanlon's What We Owe To Each Other. His formulation of moral discourse strikes me as a piece of Meta-Moral philosophy: 'An act is wrong if and only if any principle that permitted it would be one that could reasonably be rejected by people moved to find principles for the general regulation of behaviour that others, similarly motivated, could not reasonably reject’, since he seems to be dealing with what we would term terminal values without referring to them as such, but I may be off-base here.