If you make a mistake in the middle of grafting/kitchener, how can you go back one/two stitches without having to start over again.
Spread out the Kitchener seam and unpick it back past the mistake with the tapestry needle or a knitting needle. Then you need to figure out where to restart the seam. This diagram may help with the overall pattern for Kitchener.
It’s not easy to do this but you can get it right. Best is not to pause in grafting (so easy to say, so hard to do) until you’ve completed sets of the 4 steps.
That does sound like a less yarn-splitting method than my attempts of turning the darning needle around an trying to reverse its path for each stitch. As I mentioned, I often ended up splitting the yarn of a stitch or finding out where my grafting stitched had previously split the yarn. (sigh)
I recommend you to try to not use a darning needle. Instead “knit” and “purl” the Kitcheners stitch: There were you would insert the darning needle purl wise, you insert the knitting needle knit wise and vice versa. Then you use the knitting needle for pulling the yarn through.