The article on humans is what's incorrect, especially the part about humans being stronger than youkai. The only way humans are stronger than youkai is that youkai are more affected by spiritual damage than physical (which incidentally is why the spell card system works in the first place). However, I'm kind of curious as to why it survived multiple edits.
The humans that were sent into Gensokyo were essentially sent there of their own volition. They were said to possess high spiritual power and were adept at fighting youkai. But obviously, after generations of humans are born and killed and naturally die, along with the bordercrossed humans placed in the human villages, that number dwindled down. Humans are eaten by youkai if they are found outside the villages sure, and humans generally accept that fact, but the villages are protected by powerful youkai to begin with; humans have very little need to attempt to survive as the village supports them all. If all the humans died there would be massive problem for youkai anyways. Even still, youkai are free to come and go through the village and generally it's all a super-polite relationship; to the point that there are various nighttime shops catered specifically for youkai. However, in no way is there some kind of equal standing between youkai and humans. There are likely less humans than there are youkai though simply because youkai don't die for a loooooong time, and the human villages probably don't populate as quickly as one would in the outside world.
Gensokyo's humans have not ignored scientific advantages, the world just simply isn't advancing technologically at the same rate as the outside world, and for pretty obvious reasons. The kappa are just the most knowledgeable in technology. I'm sure there are various simplistic human mechanics and tradesmen, but the fact remains that Gensokyo is run mostly on the fact that there exist living creatures and there is a balance held, not that humans have invented ways to further themselves. There have undoubtedly been scientific advances, just maybe not to the point of the outside world. Also considering that Gensokyo is governed by extraordinarily powerful youkai, certain scientific advances such as weaponry are probably kept in check to keep the balance.
