I think they got KENTA because of his experience in Ring of Honor and around the US. I would seriously doubt if Triple H even watches New Japan or NOAH on a regular basis. KENTA also came highly recommended from Daniel Bryan.
That's what his scouts are for. Regal scours all the indies and other promotions for him to bring promising names to his attention. Regal was in attendance at PWG's BOLA at least once.
Gerald Brisco follows the amateur wrestling scene, especially NCAA, he brings in all the Olympic names.