Is it safe to use a portacot/travel cot that meets Australian Safety Standards instead of a normal wooden cot for an extended amount of time e.g. 6 months?

A portable/folding cot is generally accepted as being for temporary use.

Product Safety Australia (ACCC) develop & monitor safety standards & state the following:
Folding cots are designed for for temporary use. They are also known as portable cots, travel cots or portacots because they are easily collapsible for transport.
https://www.productsafety.gov.au/products/babies-kids/kids-furniture/folding-cots

Portable cots are more likely to be exposed to wear & tear when used permanently for a long period of time.
Wear and tear can expose baby to hazards. Only use a portable cot that has the mesh intact and that has no broken parts. Ensure that the base is flat and regularly check the portacot for signs of damage.
Do not use a portable cot if your child weighs more than 15kg (or check instructions of your particular model).
https://rednose.org.au/article/portable-cots