Why should changing the date/time be problematic or risky for a 3DS?
No problem changing the date/time with System Settings (will just change the offset, not the actual RTC value) and/or with GodMode9 or with ntpsync in Rosalina Menu.
The real time clock will reset if the battery is removed… so that would be a good indication that changes to the RTC aren't a big deal.
Good luck and have fun!