In the eighteenth century, Australia was more of an open-air prison then a national society in its own right, and so there was no fundamental problem with this gender imbalance.
Unfortunately I haven't found good data for the situation in the nineteenth century. On the one hand, the increase in voluntary settlers in that period may have increased the ratio of female immigrants. European men who intended to settle permanently would have been inclined to bring wives and daughters. On the other hand, continued gender imbalance would not have been surprising on the frontiers of mining and ranching. These kinds of activities often rely on a temporary and migratory labor force.
By the twentieth century, there are many organizations actively recruiting and supporting white female immigrants to Australia. To quote from an archival research guide, referring to the period of 1901-1939:
Women, especially domestic servants who were much coveted owing to the
high demand for them in Australia, were often sponsored by governments
or voluntary organisations both in Australia and Great Britain.
Non-government organisations included the Church of England Society
for Empire Settlement, the Church of England Migration Council, the
Church Army, the Domestic Immigration Society, the Society for the
Overseas Settlement of British Women (SOSBW), and the Salvation Army.
Female migration was conducted under special safeguards and
conditions, often with a matron traveling with groups of single women.
Great emphasis was placed upon their care, protection and control
before, during and after their journey to Australia. Hostels were
established in Great Britain for their training and accommodation
As a final note, I will emphasize that frontiers of European settlement around the world have frequently experienced severe gender imbalances. In many cases, it was not uncommon for male settlers to start families with native or enslaved women. In Canada, for example, fur trappers and traders took native wives which resulted in the emergence of the Métis people. Such mixing was generally discouraged by most colonial states, especially by the nineteenth century. I've not seen estimates of how extensive such inter-marriage was in Australia, but it probably did take place as evidenced by the Half-Caste Act of 1886.