Indeed, my understanding of how CI is handled is that the resulting (cruise) speed is dependent on the CI for the given conditions: altitude, weight, wind, and ISA Deviation. If the conditions aren't the exact same, the cruise speed for a given CI won't be the same. Wind and weight are two factors that have a direct influence on the speed the airplane calculates.In a headwind, the speed will become higher, in a tailwind lower as the plane tries to maximise the gain from the wind. Weight will also play a role since the plane will aim to fly at a certain AoA. A lighter plane will fly slower. A heavier one faster.