The date/time in any device is not a 'file' that you can edit, it's continuously changing variable that gets actively updated by a device's base firmware.
There's a clock chip on the logic board, or just as likely just an added feature in a primary SoC (System on a Chip) processor, that retains the date/time for the device, and as long as the device itself has an online connection the date/time will be constantly updated.
On a tablet that's running 4.2.2 (jelly Bean), that goes back almost a decade ago. Odds are the battery in it is failing so the current date/time can't be retained. Either replace the battery if possible (most tablets it's not), or leave it always plugged into its charger. But that is a very dated tablet. it's past due to upgrade to a new or newer one. JP5 devices are intended to be used only within very, very controlled, monitored settings anyway (...that's part of the installed firmware, not matter if rooted or not), Get one that's from a typical, consumer retailer. It will be much more usable without the need to 'hack' it basic functionality.