Is this sentence correct, "a wish that just a day earlier she?
It's convoluted but correct. Start with she can't think she would ever make that wish" [i.e., she can't imagine ever making that wish"], in present indicative. Then turn it into past conditional, she couldn't have thought she would ever make that wish [if it had occurred to her]. Then put it into subordinate adjective clause form. It's made tricky because of that she would ever make. If you replace that third-level subordinate clause with the non-finite verb phrase ever making", the syntax becomes clear. The nice thing about non-finite verbs is that they're non-finite, which means they don't change form when you change the time frame. But the nuance of meaning would suffer if you actually made that change.