Your team composition is bad. Kunoichi doesn't fit in this team. If you go with High Khatun or any other speed team, your goal is to wipe out the enemy team as fast as possible. None of the skills Kunoichi brings fits into this strategy.

Bring a champ with decrease def on all enemies instead. If you don't have one, go to campaign stage 10 and farm Warmaiden. Make this champ the 2nd fastest in your team, going after High Khatun, but before Ronda and Athel.

Right now, your Khatun speeds up your team and Ronda and Ahel hit hinto the full defense of your opponents. It's obvious, that this doesn't work. Reduce the def of your enemies before attacking them and your damage will increase significant.

 Also, did you pull Kunoichi from shards or did you get her using the Prime gaming reward? 

If you got her from the Prime Gaming Reward then you should also have Genbo. Drop Kunoichi and level Genbo. He's a much better Arena Champion. If you use the Savage gear you got with Ronda he hits hard (even harder if you use Warmaiden to drop Defense first). He only needs 70% Crit rate due to his A3. Fights should go like this: 

High Khatun - Fastest (make sure in lead for speed boost to team) - A2 to boost team speed and fill turn meter. 

Warmaiden - 2nd fastest - A3 - Drop Defense on all opponents. 

Genbo - A3 - boost Crit Rate & Crit Dmg 30% - extra turn - A2 to attack all opponents  

Ronda - A3 to attack all opponents and "clean up" anyone left standing. 

If you build your champions for speed you should win most fights in lower level arena.