I guess you are talking of this death certificate:
https://www.fold3.com/image/69925658...tion-1939-1948
In my own experience, the date of the loss for people who died of wounds in these documents is often the date of the wound, not the actual death date. Most of the time you will find the exact death date in the text just after vestorben.
So one possibility will be that Uffz Bondy crashed near Zagreb but was sent to an hospital in Wien and died here.
The Volksbund can be useful to point the right death date and location, but in this case there is no Bondy listed. German servicemen dying in Germany were often privately buried and so are not covered by Volksbund.
I checked the book "Verluste der deutschen Luftwaffe in Österreich September 1943 bis März 1945" and there is nothing on 10 November 1943. Lufwtaffe school losses are listed the day before and the day after.
Best regards