The responsibility for ensuring that a shared ventilation system (that is one servicing more than one Lot) performs as intended, that is as a air movement system not a odour transfer system, is that of your Owners Corporation.
So I’d suggest that you make that point in writing to your Plan’s Strata Manager (copy your Exec. Committee Sec. and your tenant), and request that that they have THEIR ventilation system inspected with a view to identifying how it’s designed to be operated, which may be with Lot fans ON, and if there is a fault, rectifying it.