Paper jounal may not be backable up, but they are not affected by bit rot, cannot be tracked or detected by any means, they are partially or totally destroyable, and helps freeing the pressuring throughts from your head, so you would be less vulnerable under torture.

Also, one can log what you type on a device even before it is encrypted (if we assume the worst scenario). So i think keeping a paper diary, even with the comfort flaws, stay the safest option (if you hide it well and doesn’t reveal its existence).