If you are using a9lh, and are afraid of breaking something related to NNID, just setup an emuNAND to region swap (unless you are using luma3DS, but I'm not too sure how far it goes with region swapping). With two NANDs, you can still access the eshop on the jpn sysNAND, and have everything you want to do online with your NA emuNAND. The NA emuNAND will have to have everything obtained from other places on the internet, but I assume you do not really care about that...