In my experience the typo-tolerance is not very flexible. I write using Dvarok instead of QWERTY, so the typos I make don't always follow regular patterns. On my phone I use a swipe keyboard, so sometimes a typo comes out as a different word entirely. No matter what I don't want to be punished for my mistakes, even if they are real mistakes. I just want to keep on learning without the tool I'm using intentionally trying to make that harder for me.