What welfare and care responsibilities do I have as a subclass 590 visa holder?

The whole basis of the Student Guardian visa is that you take responsibility for the student's wellbeing while they study in Australia. That includes their safety, suitable accommodation, and general day-to-day support.

Where a student under 18 does not have a parent or guardian living in Australia, the education provider has duty-of-care obligations and must approve suitable welfare arrangements. As the guardian you are expected to be genuinely present and involved, not just nominally responsible, throughout the student's stay.