Happy as usual to strike a nerve. Your argument is more dependent on semantics than mine.
It sounds like you want some kind of labeling system, kind of like 'USDA Organic' certification, but for news organizations. Sure, the courts could try to interpret whether or not a news organization satisfies some criteria for this label, but I wouldn't call the result of their ruling 'the truth'.
Assuming consensus could be found among 'experts', consensus isn't a magic bullet. I have no doubt this would turn into a game of cherry-picking sources and feed the litigation culture we have. I personally wouldn't attribute any increased credibility nor usefulness to any such labeling scheme. I would actually trust it less and avoid it entirely.
And yes, if such a system existed people would actually think the output of the process you describe is the absolute truth, much like a gravitational constant. It would further bifurcate our society and in the end, likely be co-opted by some political party to silence the other.