First of all I would like you to know that Mario Kart Wii is fully supported by Dolphin (PC) since years.
Problem : Mario Kart Wii display an error message when ran : "Could not write to/read from Wii system memory" on Recalbox 4.1 x64 (NUC)
This is the ONLY game that cannot access "system memory" (saves?), all of the other games can save and load properly
I read that this is sometimes caused by an accent or a forbidden character in the rom or saving path, the paths (that I saw) are default ones and I couldnt see any forbidden character such as accents or ' ! et...
I read that this is sometimes caused by a bad dump, I have tried a few different ones, EU and US, same message
My conclusion is that it might be a BUG with Recalbox 4.1, might be linked to a path / directory the game or Dolphin doesnt like, this game is known for that error...
Thanks for your answers and support