We know the score.
Seems from usage that “что к чему” is more “what’s what” than ‘the score’ - maybe it’s ‘the score’ in a colloquial sense, but if so, I feel like that’s fallen out of use recently. Definitely could be wrong but this could be worth reevaluating.
“We know what’s what” is a good translation and I added it to the original sentence at Tatoeba (the source). But I think “… the score” is fine, too, even though it’s farther from the Russian.
Interesting. On my first read, I thought it meant more in the context of a game or something, which didn’t make sense to me.