cele harb isnt better than cele cata, but if cata water attunement in cooldown, an elite elixir can kill cata easily. besides this case, cata is much more consistent and better than harb.
The comment saying cele harb is more OP than cele catalyst is insane. Cele catalyst is wayyyy more OP, just harder to play. Harb (or necro of any kind really) is very easy to lock down. Cele catalyst can truck you down like its power with hammer or burn you down like its condi on scepter while having much better defensives than necro. But that all requires the player to be good at elementalist.