After playing some more with leap attack it seems to me now that this delay between leaps is actually attack speed related. Looks like delay after each leap is longer if using slow 2h weapon vs fast 1h with ias on it. So it isnt cooldown but attack speed thing. Maybe leap attack cast rate always depended on attack speed of the weapon i have no idea honestly.
At least we can still use leap to move faster across the map even when using slow weapon since it doesnt have delay when not attacking anything.