Is there actually a way to get the AllPlayTime value? Funnily enough, it isnt shown anywhere in the normal menus is it?
Even if you can't put it back on there, it'd be a huge benefit.
If your switch is hackable (all are, but some new ones need a hardware mod) you can copy user and system (animal crossing only, ATM) saves off the console using lockpickrcm/tegraexplorer without even booting the device. I used this to get my saves off a corrupted SD card that had my emunand on it.