When I make an incorrect mark of the tone and then go back to correct it... does Skritter then act as if I didn't make the mistake? Or does it get recorded as incorrect?

I'm wanting to make sure I'm getting a true reading of my actual learning, while correcting the mistake to make sure I'm remembering correctly for next time.

It uses the last thing you submitted as the grade, overwriting any previous grade. So yeah, it will be as if you got it right the first time. If you get it wrong, look at the answer, say it to yourself, and then move onto the next one--don't retype the correct answer, or Skritter will think you were trying to a fix a typo.