You can smoothen out the fonts in Firefox by switching back to the old font rendering. Go into about:config - >
gfx.canvas.azure.backends > direct2d1.1,cairo,skia (old font rendering)
gfx.content.azure.backends > direct2d1.1,cairo,skia (old font rendering)
(compliments Aris from CustomCSSForFx)
Or if you're using CTR in Wf Classic, (the sane man's way to use Australis) navigate to the advanced column and tic the box to use Old Font Rendering. Still, the best fonts I've seen are from Advanced Chrome. They have a custom mask over DirectWrite/Skia that makes it appear suuuuper sharp and crisp. Sadly it's x86 though so the kernel doesn't yet support it.
https://browser.taokaizen.com/chrome-directwrite/