Southern Cross (and WIN and Seven QLD) are only legally to service 5 of the 7 Queensland sub-markets. They’ve picked two of their sub-markets which would be their lowest rating. There’s no legal obligation to any local news bulletins or updates. Same as how WIN broadcasts across Mackay.
Presumedly it would be a combination of neighbouring Townsville and Rockhampton stories which would be slightly or fully relevant to Mackay audiences, but possibly a Toowoomba or a Cairns story thrown in to fill time.