Queensland gets most of its rain in summer, and lawns DO tend to die off a bit in winter. Even FNQ has dry spells.
First good downpour and the grass will recover within days.
This is a very minor matter, and I can't see any tribunal upholding a claim against the tenant.
Our experience with the tribunal is that, essentially, despite what the leases say about tending gardens etc etc all they will ever uphold is (a) mowing and if your lucky (b) "doing" the edges. Tenants are not expected to weed gardens, or prune or trim trees etc. They're not expected to water. Pretty basic.
Of course you can "put up a fight" for your cracked foundations and your dead plants before the bond is refunded, but if they choose to got to the tribunal, that's our experience.
Interested to hear other experiences. Maybe we're just unlucky.
(Hence our IPs tend to have MOSTLY lawn ...)