There are a number of indigenous languages and large language families, including Algonquian, which has at least five different dialects. The same goes for the Cree and Ojibway families. There are regional variations.
I believe that it is up to each indigenous member of Parliament or senator to determine which language he or she will use, so that it becomes possible to find interpreters. In fact, it is more a matter of ensuring that we can have interpretation than of determining absolutely what the three indigenous languages spoken in the Parliament of Canada will be. I do not believe that should be rigidly established at the outset.
As you said, in a number of communities, the language has to be learned again and better taught, not only through the oral tradition, but also through the education system of the indigenous peoples themselves. Things will evolve. Basically, it is about a member or a senator choosing to speak a certain language and having an interpreter available to translate that language specifically.