Someone is about to answer this question authoritatively, so listen up. I just got off the phone with Joe Tarantino, who remastered this new set for Fantasy/Concord (and he is credited for this on the label). He confirmed that this is, indeed, a new remastering, and NOT the Japanese 20-bit K2, and that this one was done in 24-bit.
By the way, I also asked him about the new Bill Evans Vanguard box, which also credits him with remastering, and he confirmed that it, too, is a new remastering, and NOT the 20-bit-K2 remastered box previously issued in Japan.
I've called Joe in the past with questions, and he has always been very helpful. I'm glad to see that even with the Concord acquisition, he's still there.