I've never read anything about enormous bushfires or ensuing haze in Australia during the colonial period. Most European maritime explorers commented that Australia could always be seen from well out to sea thanks to the smoke of Aboriginal fires, but these were campfires, not raging bushfires. Europeans also accused Indigenous Australians of being careless or stupid with fire, but this is not the belief of historians today.

There is archaeological evidence that enormous bushfires set off by lighting were extremely common prior to Aboriginal migration into Australia 60,000+ years ago, and that it intensified during this original colonisation. Land management via fire is believed to have been a common practice amongst most prehistoric humans, and in Australia it was necessary to protect people and resources from calamity, and rapidly altered the continent's floral landscape with the spread of pyrophitic plants like eucalypts and diminishing forests.

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The historian Bill Gammage wrote extensively in his book The Biggest Estate on Earth about Aboriginal fire culture and land management, and he would tell you that there was nothing natural to Australia's forests in 1788, and that they were crafted by Indigenous Australians to be less susceptible to fire. Fire was used in hunting and land clearing, as well as for camp safety - tall grass could obscure snakes or enemy warriors, or catch alight through carelessness or lightning. Backburns and other brush management were carried out seasonally, and Gammage uses colonial paintings and written sources to show that much of Australia was cleared and 'fire safe' upon first European discovery.

Of course, enormous bushfires were always possible, caused by lightning, drought, accidents. Managament doesn't equate to absence.

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You can read more about this in:

The Biggest Estate on Earth by Bill Gammage

The First Footprints by Scott Cane