To the best of my recollection we haven't seen anything of Inspector Montalbano for some time in Australia. I think maybe Series 11 "A Den of Vipers" and "As Per Procedure", dated 2017, but I could be wrong.
I do keep a close eye on what the BBC has to offer, particularly Saturday night on BBC4, and Series 13 appeared quite recently, I think this year, again two episodes. Now Series 14, two episodes, are showing, the first aired last Saturday and the second next Saturday.
I'm surprised more recent series haven't come here yet, but what appears on BBC tends to show up in Aus sooner or later.