That's the time which she's found to be convenient for both of us to meet.

简化句子：

She's found the time to be convenient for both of us to meet.

整个划线部分为 the time 的宾补。find sth. to be adj. 结构，可以省略 to be，直接让 adj. 作宾补。

for both of us to meet，是不定式复合结构，作形容词 convenient 的补足语。