So the walkthrough probably isn't going to get updated anytime soon, I don't want to chug through thousands of lines of text either. But through the point of ctrl+f, I give thee the blessing of a pretty bad ending guide tbh.
Apart from getting character points. And also some of the requirements are like: thousands of lines apart, good luck using the 'ending condition' text file I created. It's pretty sparse and without proper guidance throughout the entire game, I'd consider some difficult.
The most difficult thing to know would be finding the bottle for Elena ending, pissing off Sophie to the point you can get her ending. One could consider Reina difficult, but her talk is easy to navigate, I guess.
I'm not too sure if there are more conditions for the ending talks, pretty sure not, but could be?