FWIW, I disagree that the final puzzle is flawed or overly difficult. (explanation after spoiler warning)
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I found it well-telegraphed by the game, given the fact that Wintercote is bolded, how often Victoria mentions Wintercote and her mother, that the 'name' command works for K but not for 13, and that K is the only character who could possibly be at Wintercote during the events of the game.
Please don't follow the suggestion to rename K to 0 or 13. That wouldn't "fix" the puzzle but would actually ruin it. 13 is Amelia West, and neither 0 or 13 make sense for K, given when she died.