I'm gonna keep this simple, I've been able to log into my American NNID on a New 3DS LL with DSES and FBI to get into the NNID settings and log in, but the eShop still hasn't worked due to mismatched regions. However, I think you could technically log into the NNID settings with a Japanese NNID, as long as you keep the region as Japan in the 3DS profile. Since I doubt anyone else ever did this, I just want to test whether this would work or not to access the eShop, so... how would I go about creating a Japanese NNID?
(In case anyone's questioning my reasoning considering a region swap would've already worked if it was considered Japanese in the region settings, my logic is if i were to swap the NNID to a Japanese one, then log in again to the working eShop, it would be able to system transfer with a American 3DS... with a Japanese NNID. It would be a bit messy, but it might work.)
(In case anyone's questioning my reasoning considering a region swap would've already worked if it was considered Japanese in the region settings, my logic is if i were to swap the NNID to a Japanese one, then log in again to the working eShop, it would be able to system transfer with a American 3DS... with a Japanese NNID. It would be a bit messy, but it might work.)