Like mentioned in the article, often times the material is very obviously suspicious and banks probably know this and still turn a blind eye to it because these borrowers are low risk and much less sensitive to the high/rising interest rates of today...
Eventually this behavior goes overboard and everything crashes. In the meantime, law-abiding people are screwed by the bubble. Then they are made to pay for the clean up.
Fraud is costly, and rationalizing it contributes to the problem.
Maybe... but you need to keep in mind most of these people are not really building a bubble. Unlike the subprime mortgage crisis, where things were built on inflated valuations, many borrowers in this "scheme" do have more than enough funds to cover the entire mortgage. It's just that their capital is relatively illiquid. This is also why the high interest rates have not significantly affected this.
The effects on housing cost is because of natural market merging where chinese properties are "overvalued" domestically. This is actually not new, and happened with Japan at some point as well.
That being said, the main risk for this is actually geopolitical... Should capital controls tighten (or, like, if war were to occur etc.) then there is a much bigger risk, but many are banking on the fact that, at least given the signs today, that is still unlikely.