modern civilization has been lucky so far, in [what / that] the crises it has had to deal with have been the kind that we can solve with money. both the american and the japanese depressions were cured by higher government spending and liquidity. true, it took a while before the solutions arrived, and both depressions [might have ended / ended] sooner if policymakers had used the right tools from the outset, or acted more quickly. however, in the end the japanese and u.s. economies still survived. and perhaps it was lucky that the solutions took hold before the damage became too great, and the entire civilization had begun to settle. it was also lucky that their examples prepared us well for dealing with the technology crash of 2000. [had it / it had] not been for that quick addition of liquidity, the aftermath could have been far worse. *liquidity (자산의) 유동성

밑줄친 부분 해석 : 그리고 아마도 손해가 너무도 커지기 전에 해결책들이 효력이 있었다는 것은 행운이었으며, 문명 전체는 안정되기 시작했다.

질문) 밑줄친부분중 안정되기 시작한게 나중일인데 왜 과거완료를 쓴걸까요
그리고 that이 진주어인데 빨간색부분도 진주어 인가요?

지문은 인터넷수능 5강의 8번지문입니다.