She wants to feel successful and confident. She was pretty proud that her awesome score was hard to beat. She knows she's not as good a player as you, but she could look at that ACDC high score with pride. She owned that score, and that was her identity on that game and to some degree, that was her identity as a pinball player, and "equal" in your relationship. Not only did you take that away from her, and then she struggled her way to a weeks worth of failure to take it back, but then the machine full erased any history of her happy success ever existing.
I hope you can feel the pain a little bit reading these words, because that's how she feels. I understand her point of view. I hurt a little just thinking about that. She just wants to feel a little successful, maybe a tiny bit on the same level as you, who is an equal in this partnership we call a marriage.
I think you gotta fully erase that GC and start over. And just a little extra: you should allow her to be a GC on a game, or when you get a high score here or there put her initials on it. That's what I do. My wife loves pinball but I'm multiple levels higher than her. She doesn't know I do this, but I put her initials into a game here and there. That way, when she says "I don't have any initials on anything" and I can feel the sadness in her voice, I point to a few games that I know do.
My wife also has a GC on a game that she's proud of. I can't beat it..... meaning, I play until I get close but then I purposely drain or tilt or something. She doesn't know I do that, it's just something that happens. Oh well.