(I deleted this comment because I just read that the devs will post the walkthrough in 3 days or later, and I was spoiling it, so pardon for my intrusion)
Ahh, no worries! Your walkthrough is very in-dept and I enjoy your commentary. I think you're better at writing the guide than I do. To be honest, I anticipated the community to post a walkthrough, and I encourage that. Right now, I have my hands occupied with feedback. It's nice to see players helping each other out. When posting guides, but sure to tag it with "Spoiler".
Note: regarding Death 8 ending; there is no point requirement, but a condition. When Ikuya asks you who you like the most and you don't pick Blace, then choose to go after him, he sends you back into the past.
Some other achievements trigger in this way too. I applaud you for finding all of the endings by yourself.
Ah well then, thanks for the permission. Here goes nothing
(REPOST, SPOILER)
Actually, the devs already answered your question also provided enough tips and clues. But here is more elaborate steps to at least avoid the death trap.
Zeikun : in Chapter 2-Hiding, if you take a wrong turn and cornered to dead end, you will literally get Death End 7(the correct escape way is left - right - left, or straight - right - straight, or right three times then straight ).
As stated by Pinlin, Zeikun's route is different from the other routes as three endings is all wrapped up and decided by the choices which Rasumi damn angel asks you about in Chapter 3-Lonely Demon. Choosing "Ha ha, it's a silly question" will give you Death End 3.
Junoru : in Chapter 2-The Hunter, if you assure Junoru not to take revenge but when Chain confronts him and you beg him to run, you'll get to Death End 1.
If you succeed in obtaining Chapter 4-Escape, you'll regret it if you chose to not intervene and you will deal with Death End 2.
Sachiro : in Chapter 2-Stories, you have to lie at least for two of the Shinigami's question whether if you have encountered supernatural event or not. Otherwise, he will "save you from your own demise" and go to Death End 5.
In Chapter 3-Awakening, when you visit Sachiro's past, choosing to pull his scarf when you are attacked by a mild dangerous spirit will lead you to Death End 6.
Kurato : if you run from or even kick the school ghost in Chapter 1-Visits, you rather deserve Death End 7.
(Answered by Pinlin) If the requirement isn't followed in which you feel like having a bit of side crush to Blace who doesn't tho in Chapter 3-Death Hours, you will be transferred through time and get Death End 8. Otherwise with enough romantic points, you will walk to Romantic Ending. Choosing to confront Kaichi instead will only lead to Normal Ending.
The key to Romantic Ending is basically listen to that sweet heavenly bell sound effect that assure you yes you are in the right path now you can relax honey. If you feel that you misheard it, you can always use the Page Up button to scroll back (I didn't count if it takes only two "bell" choices per chapter or you have to choose perfectly from Chapter 1 till the end of Chapter 3, I may get back to it later. Because I just realize that for Zeikun, there is a romance point counter to unlock the After Story). Also, Chapter 4 will be the final indication, as it has.. more optimistic title than its "normal" counterpart ;')
Anything you choose other than those above or as long as you avoid the "death" choices, it will lead you to Normal Ending and various mischievous Achievements.
*behind the scene*
Other routes : Welp, my mistakes for choosing that dumb option and wrong turns, here we go again...
Junoru's route : WHERE IS THOSE DAMN DEATH ENDINGS!! I BETTER GO DIE INSTEAD OF JUJU!
Finally found the Death Endings in his route : Kenriji family sure is suicidal or something??!! Let me die!!