If you made a backup of your NAND prior to using CFW, that would have been your safest bet. Your alternative is to wait until the community devises a tool that can wipe any traces of hacks if you care that much about not being banned.
Such a tool may only work if the Switch has never previously been online. Otherwise, if the Switch has reported to Nintendo in the past that it has 2 errors, and then later reports to Nintendo that it has 0, it could be used as a flag for a ban.
But we really don't have much proof that Switches are being banned based on error logs, aside from those being generated by LayeredFS. It could be that Nintendo never uses the number of reports and report history as a ban reason.
Luckily, if you order just the tablet portion of the Switch on eBay, without any controllers or packaging, it's cheaper. That's my plan if and when my console gets banned, since I'll already have controllers for it.