So this is how my fanmade redesigns went so far:
Kurumi - more hair, taller (i would think PNM9 Kurumi would be like 2/3 of of Mimi or Nyami, now, atleast in my headcanon designs, the height gap is reduced to just 3-4 inches with the fanmade redesign of Kurumi compared to Post-Lapistoria Mimi/Nyami)
Sapphire - Not much outside of having more hair that now covers her forehead more, and also bustier and taller.
POE-Tan - Total overhaul into a Tomboy V-Tuber, and she's not Aoi Watanabe, it's Futaba Sakuno, she retains the POE-Tan alias though.