She definitely did not have a perfect game. And yeah, she got lucky that Katurah and Jake got their wires crossed. But I think her strongest move was keeping herself and her alliance safe until they were in the majority. Her name came up a couple of times in earlier episodes, but it never went anywhere because everyone felt like they could work with her. Even though she was a member of a power couple, no one took action against her. That’s pretty rare.
I think her feelings for Austin were genuine, but she wanted to keep them separate from the game. At F5, she could have pressured him to vote Katurah with her but she told him to play his own game and do as he thought best, and he voted Julie. That probably led to her win, because Katurah and Jake would have voted her out on the revote.