You're focusing on every single atom making up 30m walls of water and producing that everytime a lightning strikes (which was basically rapid fire) all while removing all impurities from every atom to make it non conductive and doings 2 other complicated things at the same time. Are you arguing something as unquantifiable as "can process things that overload the average dude" is beyond calculating massively above 10^28 atoms and doing several other jobs at the same time with incredible speed? As for logical flaw, nah, cus this isn't just some feat that's forgotten, Shizuku made this feat in the same match that she got owned by Trackless Step. Later on she reconstructs all of her body, all of her cells. So the author forgetting something like this, is like saying "maybe the author forgot Ikki was skilled".
Kuraudo was still able to keep fighting yes, the reason, is somehow not important? It is because his reaction was practically blitzing Ikki left and right and Ikki says he didn't want to end the fight further cus he was having fun.
It is not just fear stuff, yeah, the effects of Edelweiss' aura weren't just fear stuff either, it was caused by fear but it had several effects and he fell unconscious and still kept going.
"He is Ikki" is the reason when he's the same guy who kicked a rock into the scabbard of someone like Touka Toudou who is not only immensly skilled herself for being able to pull of Trackless Step, but can actually read minds. So he kicked with a rock a very skilled girl who can read all of his thoughts. Then again, Trackless Step, until you show me a better feat than those of Shizuku, they'll work. If you need more perception feats there is SSSAF Ikki being able to count every speck of dust hitting his skin, every strand of hair on Stella's hair, his own heart beat etc etc at the same time, yet still being vulnerable to Trackless Step because he still has an unconsciousness (i mean he's not vulnerable then, cus he can tap into his unconsciousness, but i meant even perceiving all of that at once is not enough).