Perhaps your scorekeeper should be told that errors aren't about evaluating the quality of throws. They are about accounting for how batters and runners reach base and advance.
Lots of infielders make terrible throws that end up as successful defensive chances because first basemen make great scoops, stretches, or swipe tags. Lots of awful throws from the outfield end up as nothing because a fortuitous backup or rebound prevents an advance. Does your scorekeeper want to start charging players with errors for bad throws, regardless of how the play turns out?
Also, I'm curious as to how she thinks charging the catcher with a phantom PB helps him more than charging him with the error that properly explains the runner's subsequent advance.