Turns out, hover has no counters to Kodachi. When a Kodachi is microed perfectly, it hard-counters Bolas. It's speed,range and turnrate is just too fast. (Please don't even suggest making Daggers against Kodachis.)

Kodachi doesn't scale nicely though. The friendly fire gets bad when moving into an enemy army and they can't range dance when there's more than one.
They also only work against Bolas moving towards them and MUST be microd.
Unmicrod Bola vs unmicrod Kodachi is normally a win for the Bola.
I think a well microd Bola and a well microd Kodachi will stalemate but would need to check.

It's definitely not a "hard-counter" though.

The best counter hover has for kodachis is massed scalpels, as far as I can tell. In small numbers kodachis can still juke them reasonably effectively and get good trades, but it gets progressively harder as the size of the scalpel ball increases. And mace does a fairly good job of defending the scalpels. The other best counter vs kodachi is stardust.

But yeah bolas just can't do it unless the tank player fails their micro check, because of the huge range bonus they get while retreating, and even the scalpel ball has a lot of drawbacks.