I see what you meant, now - no, I have not seen SC stars (it could be CS stars), yet, and I don't think anyone in this thread has as it would have been reported.Sure, MS class stars have progressed from M class, and have not yet become S class, while the description says they have progressed from S class. It's likely just a typo, though I have searched for SC class stars to no avail.
Plenty of other problems with descriptions and consistency, such as the limited number of giants and supergiants. Class B supergiants show as class A, class G supergiants show as class F, and class K supergiants show as class M. Meanwhile, class M sub-giants are giants, while class B giants are normal stars.
BTW, quite a collection of description bugs you have. Why have you not shared them earlier? They are very important as far as the book is concerned.
Trav ElEr and Patau, do you now see the scale of the problem? It's quite probable those are not all description bugs, yet.