The logic analysis of anti-reality hypothesis compound sentence is to reveal its hidden logic thinking modalities which are different reasoning,counterevidence and figurative reasoning.
The extravagance and general profligacy which he scrupled not to lay to Mr. Wickham's charge, exceedingly shocked her; the more so, as she could bring no proof of its injustice.
Corrie says, " I consider that counterevidence." In other words, she's listened to Aaron sing, and she doesn't think that the singing talent that Aaron has is anything like the singing talent that Elvis Presley had.
That's why she says that Aaron's singing is " counterevidence." Counterevidence would be some indication, some fact, that would show that what you are saying is not true or is not possible.