She's also not losing the hand at the time she called, percentage wise, unless you factor in the cards folded by the other players. We don't know if she had that information.
It was effectively a coin flip given how many outs he had and the fact that her hand was better at the turn.
Saying she needed to cheat to win a coin flip is just weird.
Also the fact that it is a coin flip is well known in the poker community. If you haven't heard people bitching about losing to JX you haven't played enough.
I think if she cheated (I don't have any strong opinions on whether she did), that her signal was binary. It makes the most sense given her actions, and inability to explain them.
Buzzer that buzzes when "you have the best hand right now" makes a lot of sense and is easy for a bad player to understand.
It's a coin flip, but she's 55% favorite unless she knows the discarded/dead cards. If she knows them, she has 47% equity which makes her call very profitable given the pot size of 40k.
This is basic "pot odds" or EV calculation, I encourage you to do it.
If she didn't know his exact hand, her play is unspeakably bad. She has virtually zero equity against Garrett's range here. He's holding one of the two or three hands she can beat given his line. Most of his bluffs are crushing her.
Also the whole counterpoint hinges on not believing she felt she was calling a bluff which she explicitly called her plays as being.