Talking about Komachi, at the time of PoFV she said to Marisa that she was 10 years too young to think about her own death. I know it probably didn't have much meaning, but now it's exactly 10 years from that thing...
"Ten years too early" is a common Japanese phrase for chiding someone for their immaturity and lack of experience. Its variations have appeared more than once in Touhou. For an anime-style story it's typically used like this: "you are ten years too early to think of defeating me!" i.e. "go and train for another ten years before thinking of defeating me!"
The joke here is that Komachi used the phrase in a way that makes no logical sense, and Marisa immediately called her out. You shouldn't read too much into it.
Speaking of that, because the Touhou game scenarios are written as manzai comedy, I've been thinking that from a writing standpoint, the most important quality a main game playable character can have is NOT intelligence, or diligence, or any of the things you expect from a hero, but rather to play the part of the straight man well. They don't need to figure out the truth; rather, they should react to the ridiculous things the newly introduced bosses said in a funny way, and incite the bosses to say even funnier things.