She can efficiently abuse three keystones.
Which keystones is she "abusing"? Fiora may have a flexible rune path but she is not abusing any of them. The only one i can see that you're saying she "abuses" is Conquerer, but that's because the rune itself is busted, not the character using it.
Maximum health % True damage.
That takes a while to scale and come online. That's why its balanced because the damage doesn't become noticeable until mid-late game, which in this early game meta is not very useful. That's why her true damage is balanced because it takes so long to start being useful.
Short cooldown mobility with 60% cooldown refund.
The range on Q is short and her mobility is only high in combat once she gets CDR. The cool down without hitting something is quite high for how low the range is. 16 / 14 / 12 / 10 / 8 on a short range dash is pretty high considering its her only gap closing ability. The cooldown is only low with the refund.
Remove the cripple from W so people can fight back instead of lowering it by 50% for 1.5 seconds.
Or they could, you know, dodge the delayed skill shot, like any other champion ability. Its still a stand alone ability and skillshot with a high CD, no reason it should have to be gutted jsut because you cant dodge. Riposte has a 24 / 22 / 20 / 18 / 16 CD and considering its the last ability to be maxed means its running a 24 second CD the majority of the game and it only fires after a delay, you can dodge it, you can walk to the right or left in that time.
Remove the 60% cooldown refund on Q
And this is how its obvious to tell you're calling for nerfs on a champ you've never touched. Fiora's Q is her main ability, her bread and butter skill. In every engagement and every fight Fiora will be using this ability, its absolutely vital to the champion. She is 100% balanced around this ability. When Fiora was first reworked and the cooldown was just a little higher, she couldn't function. This ability needs a low cooldown, other wise she just doesn't work. The mobility in her kit, the MS on ult/passive and Q all works together to make the champ work, without all of it, she just flops.