You can get historical
traffic data on the Nav screen by going to Navigation Info -> Traffic -> Traffic History. You can even zoom in/out and look at other cities' historical traffic data.
Interestingly enough, there is a Current Traffic menu option that is grayed out which corroborates what MazdaConnect Support told Chris Brown, ie: They're still working on it, hopefully it will be available some time in the future.
Pictures of Nav screen's Historical Traffic Data:
2016 Mazda 6 Nav Screen Historical Traffic - Album on Imgur