It's an easy fix, it must be. I'm sure it was just overlooked since most people don't bother with notebooks. I use one notebook in almost every world for coordinates of natural formations, villages, temples and all that, I also use notebooks for checklists (which currently is a pain because of this bug/missing feature) and most importantly main goals, like collecting an amount of xp for my planned enchant.
It's an easy fix, it must be. I'm sure it was just overlooked since most people don't bother with notebooks. I use one notebook in almost every world for coordinates of natural formations, villages, temples and all that, I also use notebooks for checklists (which currently is a pain because of this bug/missing feature) and most importantly main goals, like collecting an amount of xp for my planned enchant.