About "fiend": I forgot the whole running gag of "vampires have oni weaknesses".
>General
Some line clusters are too close, and could be more spread out, especially those above Luna and to the left of Sakuya.
>Aki sisters and "Autumn Season"
SoPM says Shizuha is mostly active in Youkai Mountain and Forest of Magic, while Minoriko is mostly active in Human Village. It's better to separate "Autumn Season" out from Youkai Mountain, since like Lily White, they can appear in all of Gensokyo.
>Locations
To be strict, "Inside the Clouds" and "Bhava agra" (both are parts of the Heavens), and "Underworld" (Former Hell) all should be "Not in Gensokyo". At most, "Inside the Clouds" and upper levels of Underworld can be debateable.
The color coding for location types could be more distinctive.
>"Exact Location Unknown" tag
This... creates additional trouble. Anyway, Suika really needs it (as one of the most powerful characters who can also turn into mist, she can be anywhere she wants), while Letty doesn't need it more than Lily White does.
>Okuu
There's a small mistranslation on the current wiki SoPM Utsuho
entry. The Yatagarasu in Okuu is a 分霊, a partition of Yatagarasu ("gods can be infinitely divided"), not the whole god. And yeah, even the part in Okuu is still quite alive. That's why the vessel must have a simple mind, to avoid conflict with the god. So Okuu has definitely not absorbed Yatagarasu.
It's better to add Yatagarasu. My suggestion: Okuu is its "vessel", and Kanako's line points to the "vessel" node: she "arranged" it, something like that.
>Miko
First of all, Miko is divine, because she's a historical figure who has been worshipped as a god after her "death".
The small divine spirits are human prayers and wishes, that is to say, raw faith itself. In theory, a god should give blessings in return of the faith, but Miko instead seems to prefer to take advantage of people by listening to their desires.
Yuyuko is a true glutton. She ate her snacks very fast in SSiB, and Sakuya joked about her gluttony in Soku.
Ran is a nine-tailed fox. The description should emphasize this before everything else.
Unzan's title is "The Big Wheel That Guards and is Guarded", his "Guardian" status with Ichirin is mutual. There's no evidence that he was once human, and nyuudou don't have to be former humans, so he should be... "Unclassified"?