It seems that even Slashdot has slow news weeks.
The standard view on Polar Bear population levels is that they've rebounded since controls were put on hunting. This has, of course, absolutely nothing to do with the possibility of habitat loss hammering their numbers in the future.
The Mosquito was a very successful aircraft - there was a problem with a few Canadian-built ones vanishing crossing the Atlantic, I believe, but apart from that they were very solid. And very fast.
All I've seen are statements that Northrop finds the plane stealthy. I've no problem with that. What I haven't seen are statements from them that the carbon inclusions are a significant part of this. The articles all imply that this is the case, but they don't directly quote anyone from Northrop saying so or mention a test that would specifically determine this.
I am sure that, as you say, those involved with the tests know what the contribution of the carbon was, but the articles are actually quite vague on the point.
Whether it actually reduced radar signature is an issue here, and without doing a comparison of leading edges with and without the added carbon, how do we know that the slight signature wasn't simply due to the small size and low metal content?
"Spock, did you see the looks on their faces?" "Yes, Captain, a sort of vacant contentment."