Regardless of whether or not she knew, it would be a huge leap to consider this as cheating. I consider cheating as a situation in which, as the shooter, you are in a position in which you are the only one who knows you have fouled and you fail to call it on yourself - such as a double hit on the cue ball that is so slight that the shooter is the only one that knows, or the shooter's body was blocking the view of the opponent being able to potentially call the double hit. Or in a case when the opponent claims that the shooter has fouled such as on a bad hit, but the shooter denies it even though they know it was a bad hit. That is completely different than bailing out your opponent for not paying attention when they should have been, particularly in a hill-hill game.
I have witnessed this very exact scenario that occurred between these two ladies play out in our tournaments in which I'm the TD. I've learned to stay out of it and say nothing, and that's how it has to be. Players have the responsibility to pay attention during their match and I'm not going to bail out a player for not paying attention when they should have been, and a spectator should not be permitted to do so either. However, in the case of an opponent claiming a bad hit on the shooter and the shooter denying it, if I was observing and in a good position to make the call and I clearly witnessed it as TD, and I know for absolute certainty that it was a bad hit, even if I hadn't been called to the table to judge the shot, I will step in to resolve the conflict with the correct call as I saw it.