Your idea sounds interesting but this problem which you yourself has said in the last paragraph, I am quoting you...
Typical fraud with fire insurances would be to burn my house after insuring it with several insurances. Our bitcoin insurance would have the problem that I could even run 10 contracts and resolve all ten in parallel as long as there is no central authority matching incidences and there are enough members that an overlap of judges won't occur but I'm sure either other insurances that are easier to identify could work that way or some of you has a good idea to tackle this concern.
Will cause all sort of problems and can bring an end to the project. Real life insurance should be having a solution for sure. I think they what they so it, even if you insure your house which has a total value of let say a 1 million USD, then if you take out 10 insurance policy, and your house get burnt and after the investigation they found that it's an accident and the insurance agreement covers it then, all the 10 insurance companies will pay you 100,000 USD and total you will get 1 million. You won't be allowed to make good or profit out of your loss
You will have to implement something like this.