Hi - Xayah main here. And these nerfs are going to make her early game miserable without really hitting what I see as the actual offender here - Xayah's lategame scaling. The W buff to 40/47.5/55/62.5/70% attack speed is somewhat overkill, and can be reverted, or even just reduced. That would tone Xayah's power level down without making her feel miserable early. 25 armor is incredibly low, even for an adc, and a nearly 3 minute cooldown on a rank 1 ultimate is insane, even considering what her ult does. Please consider reverting the W buff instead of this. 30/35/40/45/50% is still pretty good for an attack speed steroid.
Seriously Riot. Think long and hard before you make these changes. At the very, very least, just use the ultimate cooldown nerf, not the armor nerf as well.