For some reason I think it's changeable without any big fuss of swapping the cluster or software. Just because firstly miles is in digital format, so it can be easily displayed in KM and car companies these days uses same hardware with different settings and config for different regions. Secondly Speedometer dial carries KM and Miles.
Have you tried speaking to Kia dealer on this subject?
Yes the instrument cluster.
What you could try first is going to one of the mileage correction guys (the clockers in Sharjah) and ask them if they can flash the clocks with GCC or Australian software. If they're any good at their job they'll be able to tell you if it's possible but I'm guessing most of them only know how to use their software for anything other than rewinding the kms.