any chance that you can update that tutorial to mach the new behaviour?
in the knowledge base, you mentioned 2 solutions, but the first one isn`t working, that leaves us the second one with the expressions, but as a beginner, tbh I have no idea how to change the rotation angle or rotate the books to the opposite direction and it feels overcomplicated anyway.
I only work on interiors and I mainly bought railclone for books, bookcases and railings and this is slightly disappointing because you "forgot" to mention at the tutorials that the software has changed since then.