You're right about the liver but as ever the question as to whether something is bad for us comes down to how much we consume. Apple seeds along with a number of other fruits contain amygdalin which breaks down to cyanide. So there's cyanide in apple juice but we'd have to drink several tens of liters of the stuff to reach anything approaching a lethal dose. We can handle small amounts of cyanide. Similar story with fructose, admittedly on a rather different level. However the dangers are real.

Robert Lustig explains the issue here: https://robertlustig.com/fructose2/ and this [ https://journals.physiology.org/doi/pdf/10.1152/physrev.0001... ] provides a readable account of the problem if fructose consumption rises above a certain level.