Kinda sucks I can't play SMarioMaker or MK7 online, but I guess I can live with that. But it's gonna be a problem if I can't sustain myself with FBI, FreShop, or CIAngel. Unless one of those has a 3dsx version and I can figure out how to get back into HBL. Also, what exactly is your definition of an "unsafe" Cia, because other than pirated games, I have a theme changer, HBL, Luma3ds Updater, Ciaangel, etc. Will those also trigger Ninty when launched?You will be able to.
I can't say for sure how you got banned, but keep in mind anything you run while online is logged on Nintendo's servers. If you run homebrew CIAs or VC injects while online they can detect it and potentially ban you.
Your last running title is sent to their servers if you have nothing running.
It doesn't matter if SpotPass is on or off, the data is still sent to Nintendo's servers.
Launching .3dsx homebrew through Rosalina is safer, since they'll only see you as running Download Play.
By keeping this in mind and only running unsafe CIAs while offline, you can lessen the chance of bans. It's not known exactly what criteria Nintendo uses to ban (besides obviously playing leaked games online before release), but this is a pretty easy way for them to tell if people are using CFW.
It doesn't block all their servers, it's only meant for blocking updates.
So, besides unbanning my 3ds, what will my sister's private seed do? (change friend code, etc.) And if we both want to play together/ StreetPass / our 3dss are on and on the Internet at the same time, will it TRIGGER Ninty?Use this to extract your sisters private seed and inject it into your 3ds https://gbatemp.net/threads/all-3-methods-to-get-unbanned-from-recent-ban-wave.450679/
Since you will both be using private seeds,the chances of you getting banned again are very low,unless you want to go public,then you will want to find as many spare public seeds as you can scattered around the internet.