I also think it would be great if you could give us the .js file and ability of knowing how to edit and share with other users so that we can make custom assignments of our own, I love the custom assignments given to us by bblog to do but what would make this even better would be that ability to set goals and challenges of your own to friends and clan mates.
There is no API for that, so you need to know what strings to use from battlereports and for that there is also no list. So it's pretty much pointless, cause you wouldn't know what to add to make it work.
As juress said, the data of the battlereport is very complicated.
Also you must know much about coding and that stuff to make it working.
And also you need access ot the BBLog Server to make assignments working that need battlereport data.