Who says Renault aren't promoting the product in Australia. At least they are backing the Meganes heavily in TCR racing, and involvement is increasing for 2020, starting with the Melbourne F1 GP in March.
And with free-to-air coverage on Ch 7 in 2020, there is plenty of coverage to be had.
Also Garry Rogers Motorsport has partnered with the Swiss builder of the Megane TCR to carry out more development in Australia, with a new and upgraded car coming.

A couple of articles here:

TCR Australia on Facebook: Can James Moffat & Renault Sport GRM be a genuine threat in 2020 TCR Australia?

And from Renault Australia website news:

(Posted in both Renault and Motorsport forums on AF).