So I finally found a second hand H2o2, it's a version 2.
I can start plato using NiLuJe's kfmon but the touchscreen doesn't work as intended: to have an action on the right side of the screen, I have to put my finder on the extreme left.
If that's of any help, to be able to get koreader working I've had to use
NiLuJe's latest config file
I tried the double finger swap, it doesn't leave anything special in info.log (there's only "Plato is running on a Kobo Aura H₂O Edition 2. The framebuffer resolution is 1080 by 1440.").
That said, plato looks really nice, thanks for this great app!