Since when have Explanatory Memoranda been used to help judges, as you say, in the interpretation of a Law?
The EM exists to help members of parliament in giving background to and interpreting the intent behind what law is being proposed in a Bill put to Parliament for debate.
The difference between the two may be fine, but what may be practical and necessary for the Legislature may well be "inadmissable evidence" for the Judiciary.
All that aside, there is in the opinion of some Constitutional lawyers that the Voice can advise on ANY matters, and that the EM could be misleading.
The use of the word "including" in the EM is the problem. "Including" does not mean "is limited to".
It should be a worry to voters therefore that even constitutional lawyers aren't consensual, and a number have complained their views weren't taken on board by the Labor-stacked Review committee.
