I saw in a Facebook post that you are able to see at least one of these falls from the Kalihiwai River Bridge, and that you are able to park nearby and walk down to the bridge.
First, there is no parking some 300 yards east of the Kalihiwai Bridge as the Facebook post says, or even up to mile marker 24. Maybe there is a spot where you might be able to park one car, but you would be right up against Kuhio Hwy.
The closest place I found to park was ½ mile west of the bridge. I then walked down the bridge. There is very little room on either side of Kuhio Hwy to walk. You are within 6 feet or so of busy traffic on Kuhio Hwy.
Then when I got to the bridge, there was even less room to walk. You are even closer to traffic on the highway side, and the railing for the bridge is maybe knee to thigh high. This is incredibly dangerous. If you fall, good luck. You either fall over the railing or you fall into oncoming traffic. NO ONE SHOULD EVER WALK OUT ONTO THAT BRIDGE.
However, I did because having done all this, I wanted to at least see if the falls were worth a look. HELLO! There are no falls visible, from either side of the bridge!
My assessment is that the Facebook post was perhaps written by some Russian troll who is trying to get someone killed.