Kata is broken in the same way YI is Broken: either your setup has the tools to hardcounter her, or your royaly screwed
You really need instant hard cc to deal with a well played kata, her burst comes within a split second, you can't do anything against that, and she has a masiive ms boost afterwards to get away, and if she gets a reset, you won't be able to pin her down anyway. Most not so well played katas always trie to get their ult channled, but saidly the massive damage on a full channled ult isn't what makes kata powerfull, it's how mobile she is, how fast and inevitable her burst is and mostly the resets.
Trying to channle the ulr just makes you an easy target and very vulnerable to burst and cc, so you have to be very thoughtfull on when and mostly how long to channle it.
Her main thing stays cleaning up fights with mobillity+resets.