Were there any assassinations of high-profile Austrian officials before that of the Archduke Ferdinand?

First of all, i wouldn't say Archduke Franz Ferdinand was at all important - let's not forget, even though he was the heir presumtive, he was in a mortganatic marriage, so in any case the titles would have passed to his brother and his heirs. The Austrian response had nothing to do with Franz Ferdinand - they would have probably reacted the same if the Black Hand had murdered a.. simple Austrian soldier(speculation, but mostly founded). The Austrians wanted land, to prove they were still a force to be reckoned with, and tensions in Europe were really high.

And secondly, more to the point - no, there weren't any high profile Austrian victims of Serbian extremism(at least not to my knowledge).

There is an conspiracy theory, where Rudolf, the crown Prince of Austria was murdered. Official documents reports that he died in an act of suicide.

More details about Rudolf here: https://en.wikipedia.org/wiki/Rudolf,_Crown_Prince_of_Austria#Affairs_and_suicide

In 1853 the emperor Franz Joseph himself had to suffer an assassination attempt. And he was certainly high-profile enough to be at the center of attention for all would-be assassins for his whole life. Only by chance he avoided that fate later, as he was also the prime target for the Black Hand that eventually settled for the archduke:

In 1911, Dimitrijević organised an attempt to assassinate the octogenarian Austrian Emperor Franz Josef. When this failed, Dimitrijević turned his attention to the heir to the throne, Archduke Franz Ferdinand.

But for the background given in the question, it might be of interest that not only Serbian/Bosnian operations clashed with Austria-Hungary's plans, but also:

Austria-Hungary, struggling for an exit from the Adriatic and seeking ways for expansion in the south at the expense of the Ottoman Empire, was totally opposed to any other nation's expansion in the area. At the same time, the Habsburg empire had its own internal problems with the significant Slav populations that campaigned against the German–Hungarian control of the multinational state. Serbia, whose aspirations in the direction of the Austrian-held Bosnia were no secret, was considered an enemy and the main tool of Russian machinations that were behind the agitation of Austria's Slav subjects. But the Habsburgs failed to achieve German backup for a firm reaction. Initially, Emperor Wilhelm II told the Archduke Franz Ferdinand that Germany was ready to support Austria in all circumstances – even at the risk of a world war, but the Austro-Hungarians hesitated. Finally, in the German Imperial War Council of 8 December 1912 the consensus was that Germany would not be ready for war until at least mid-1914 and notes about that passed to the Habsburgs. Consequently, no actions could be taken when the Serbs acceded to the Austrian ultimatum of 18 October and withdrew from Albania.

Even the Serbian king Alexander I of Serbia was assassinated in part or even mainly because he was "too friendly to Austria-Hungary" in 1903.

Bogdan Žerajić who also wanted to have a shot at the emperor then went

on 15 June 1910, Žerajić attempted to assassinate Varešanin on the day of opening of the Austro-Hungarian Diet of Bosnia because he believed it was illegal and illegitimate.9 He shot at Varešanin five times, and missed. With his last, sixth, bullet Žerajić killed himself. Before he died, he said that he expected that Serbdom would avenge his death. His action brought Young Bosnia to the public attention.

Even in January 1914 Oskar Potiorek (Feldzeugmeister of the kuk Army and governor of Bosnia and Herzegovina at the time) was targeted by Muhamed Mehmedbašić, who was also involved in the later shooting of Franz-Ferdinand.

Count Andrzej Potocki, the governor of Galicia, was assassinated on April 12, 1908 in Lemberg (Lviv) by a Ruthenian (i.e. Ukrainian) student.

There were also several unsuccessful assassination attempts:

• on general Marijan Varešanin, the governor of Bosnia and Herzegovina, on June 15, 1910 in Sarajevo by a Bosnian Serb,
• on count István Tisza, the speaker of the House of Representatives, on June 7, 1912 in Budapest by a Hungarian (he would be assassinated by Hungarian soldiers on October 31, 1918),
• on Slavko Cuvaj, the ban of Croatia, on June 8, 1912 in Zagreb by Croatians,
• on baron Iván Skerlecz, the next ban of Croatia, on August 18, 1913 in Zagreb by a Croatian,
• on István Miklósy, the Greek Catholic archbishop of Hajdúdorog, on February 23, 1914 in Debrecen by Romanians.