'May' is used, (in addition to other reasons) because otherwise it creates a legal obligation on the Voice, to make representations.

Then that would have to be regulated by parliamentary legislation, stating exactly when and how often the Voice legally has to make representations (once a year? Twice a year?) and when exactly.

Even your example of 'the legislature and executive "shall receive" representations from the Voice' sets up the necessity of creating parliamentary legistion to regulate, as they would be needed to define how often and in what form (Email? Formal oration to shared session of HoR and Senate? Document submitted to Cabinet? Oration to Cabinet in a specific ceremonial format? Or to Department of Prime Minister and Cabinet?) those representations are to be made, in order for parliament to "receive them"

And "shall receive" still puts the legal/constitutional obligation on the Voice to come up with and present those representations, (even if they've nothing important to say at that time, or need more time to discuss an issue) and then obey all those parliamentary regulations in order to fulfil the constitutional obligations you've just created.

The current wording allows that a formal constitutional body, calling itself the Aboriginal and Torres Strait Islander Voice, may make representations to Parliament and the Executive, and therefore that those representations will be formally recognised as coming from a constitutionally enshrined and recognised Aboriginal and Torres Strait Islander entity. The current wording doesn't force them to make representations, and more importantly, doesn't mean the creation and the Voice having to follow strict rules about when, how, and how often those representations are made.

With the current wording, if the Voice decided they wanted to present their representation as a handwritten piece of paper hand-delivered to the Prime Minister, they could. Because any legislation that blocks the Voice from making a representation to the Executive would be found unconstitutional. And any legislation moderating and regulating how the Voice can make those representations could be potentially challenged in the High Court if they negatively impinge the Voice's ability to make those representations.

Basically, the current constitutional wording allows for the creation of an ATSI Voice that can't be told to shut up.

And also importantly, can't be closed down and discontinued through a legislative act of parliament.

....... legalese on a countries constitution and your fee fees on 'weasel words' have zero relation to one another. Please stop.