I think the motion that sets out the committee's mandate sets it out in terms of values that an electoral system must reflect. There's no resolution, or unambiguous resolution, to satisfy all those conditions. In some cases, it's because we can't define, for example, what democratic will is, or it's hard to agree on what accountability is, and so on.
It's hard, then, to measure the trade-off we confront. What would be a better way to phrase this? If the mandate said to choose a more proportional electoral system, that's unambiguous. Right? I can measure the proportionality of an electoral system, and I can choose a proportional one.
If you want one that is decisive at the electoral stage rather than at the parliamentary stage, you ought to choose a disproportional system, a winner-take-all kind of system.
Proportionality is a value-free metric in some ways. It merely says that the slope between votes and seats is equal to one. Under an electoral system, it is or is not equal to one. That can be assessed unambiguously. As to the rest of this, I don't know how you assess these values unambiguously.