If a Torah reader finds certain writing errors in a Torah scroll, the scroll may be invalid, and the congregation would be required to take out a different one to continue the service. Some errors, however, are considered minor, and the service could be continued using that scroll, with the error to be fixed at a later time.
In a discussion of possible errors in the "laws" section of my Tikkun (Jerusalem: Mishor, 1990), one was mentioned at Genesis 3:24: the verse ends, "לשמר את דרך עץ החיים" -- "to keep the way of the tree of life". The issue deals with the final Kaf ך of the word דרך (way). If the Kaf is הפוכה (inverted), then you could continue reading from that scroll. But if the Kaf is כפופה (bent over; that is, it was written כ, as its medial form), then a new one must be taken out.
What is the background for these rules? Why would someone want to invert or bend/medialize the Kaf on this particular verse, and if so, why is one worse than the other?