Subterranean Animism and Double Dealing Character as well as Hopeless Masquerade and Mountain of Faith were also major incidents.
No, not really. Subterranean Animism was going to end without issue anyway, even if Reimu and co. did not travel down to investigate. Orin caused a ruckus because she feared that the Oni would punish Okuu if Okuu is going to try something funny.
Nothing in Double Dealing Character was going to vastly affect humans. Their weapons went out of control for a bit. I don't see how that is a major incident.
Hopeless Masquerade, yes, that is a major incident. Since not fixing Kokoro means village is doomed.
Mountain of Faith is already mentioned.
Now, Urban Legend in Limbo, seems like it is scaling to be a major incident.
Edit: *
Now, Urban Legend in Limbo, seems like it is scaling to be a major incident.Wrong game name, it should be Legacy of Lunatic Kingdom, hopefully it was understood from context.