That is a major oversight by Plarium. They need to fix it because that makes no sense. I'm not doing this event, but for anyone who does, this is a major blow to their planning. 

HH has done a quick video about this though it highlights the same issue on the left hand path - someone at Plarium obviously has no idea how to correctly design a tree, if the link is there it should allow access, if no access is intended the link should not be there in either tree

So the path on far right is a dead end at the rare book? 

That seems odd, is the error in the display or should that path be viable.   The latter seems how it should be...

No, the path on the right is a valid path, and does allow you to reach the end of the tree. However, it does not lead to the key - which means you cannot progress past the step a bit further down which requires one.

Ahh, got it.  So the horizontal line to the left is "broken"?

Any mods have a comment on whether this is a graphical error or not?

Here's another image that may help demonstrate:

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Just in case that may help somebody. In the actual path event, you can go horizontal in the tree. 

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