句中不定式的使用方法

The government officials were unprepared for some of those returning on the evacuation flights to have been stranded for so long that their original flights made them eligible for free hotel quarantine.

我了解to have been stranded是做those的后置定语，那样请问：

1. 这个不定式表示的状况发生在return之前还是谓语动词were unprepared之前呢？

2. 为何不需要having been stranded，从而和returning维持一致呢？

谢谢回答

The government officials were unprepared for some of those returning on the evacuation flights to have been stranded for so long that their original flights made them eligible for free hotel quarantine.
1. were unprepared for ：没预料到；没筹备到
2. some of those returning on the evacuation flights：returning on the evacuation flights （乘坐撤离航班返回的）目前分词作 some of those（人）的定语。
3. the evacuation flights to have been stranded for so long：to have been stranded for so long 不定式作 the evacuation flights 的定语，完成体表示 “航班被滞留” 的时间早于 returning。
4. that their original flights made them eligible for free hotel quarantine：结果状语从句。