Next time use a heat gun and warm that plastic hose up as much as necessary. The brass insert helps to stabilize the plastic hose cause when you tighten the nut onto the elbow it crushes the brass sleeve onto the plastic hose making a nice seal. So if you have the brass insert pushed in to where you have stated then it will probably work ok. This statement is based on the authors personal experiences and other opinions may very.
As a reminder there has been a lot of discussion about using thread sealant on the connections so you might want to research that. I'm not sure what you have available in Australia