I have been checking through the various papers I have from the research carried out by my grandmother some 60 years ago, or more! There is much about the Broun's of Colstoun but I cannot find a definite link to the Australian branch, although it is mentioned that the baronetcy passed to 'an uncle living in Australia". If you contact me by email (at email@example.com I will send you some more information (Note: remove the y's to get correct address).
I have found two pages torn out of a book that list the various members of the Broun baronetage - the page heading is Peerage and Baronteage but I do not know if that is the title of the book or merely a section. The date of it is not given but I would guess it is from the beginning of the 20thC - the latest date I can see from a quick search is 1910. It says that Sir William 10th Bt is the "current bart". The document gives details of the barons and their offspring. Of direct use to you maybe that the 7th baronet (Unknown in your list) was Sir James, son of 6th Baronet, and he was born 12 March 1768 and died 30 Nov 1844. He was father of Richard 8th Bt and William 9th Bt.