I believe that values are complex because I observe the apparent values to be complex and because I haven't seen a simple value system which wouldn't contradict both actual human behaviour and expressed preferences in some respect.

our "actual" values to be the values we would endorse in reflective equilibrium

Are there reasons to think that there is a reflective equilibrium and that it is unique? Anyway, if I had to construct an equilibrium, I would try to make it as close to the unstable apparent values which I endorse now and since this system is complex, the approximation may be complex as well. It is certainly possible to define a simple equilibrious value system, but I would be wary to talk about human values then.