I don't recommend Fleet Footwork on Kalista. Most ADCs can make use of it since they build a lot of AD items or build a lot of crit, but Kalista doesn't really do that. For these reasons, Press the Attack and Lethal Tempo are immensely better to take. I recommend removing it from the guide section since you said it sucks.

Have you considered Gathering Storm + Absolute Focus (or + Celerity)? Since Kalista is a late game ADC, I think Gathering Storm would be a great pick up on her since she is meant to scale up for late game. Sudden Impact is more of an early game rune and they just nerfed it. Eyeball Collection seems good, but is easily out-performed by Absolute Focus and Gathering Storm when you reach 30 minutes.

Great Guide, I am quite a **** player so thanks for telling me what to build, i decided to take lethal tempo as i love attack speed but could u please explain the disadvantages of lethal tempo to pta. Thanks.