These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Epileptic Trees: Anything to do with the Spirits backstory counts as this, seeing how they're one of the few things that never gets much detail as to what life was like before the start of the game. The Book of Prophecies former Chosen Ones can count too.
Fan-Preferred Couple: Every single couple has its fair share of fans, but Anwar/Tia has a very notable fanbase, followed by Valdo/Tia and Ur/Tia. On the flip side, Yumil is often paired with Dorothea.
Ho Yay: Gustav, from of all people, will commend to you that if he was 20 years younger he'll definitely court you.
The codes themselves may very well count, due to how difficult it is to keep track of them. There's also no search option, meaning you need to flip through page after page until you find the code you want (sometimes you need a certain size, due to the amount of codes required for your goal being the maximum amount you can place) meaning it can easily add up to hours of searching for codes throughout the game. Hell, most of the gimmicks count, due to poor execution. Even giving items is a pain, due to requiring MP to give the items.
Judgment Links by virtue of being on the same button as the search button. Searching for the spots on the map where you get CP becomes even longer when you have to pause for your character to swing their weapons around.