Don't think the random hook throws added anything to it.
Many things that need to be targetted on walkable terrain will automatically go to the nearest terrain when cast on a wall. This can let you place some slightly longer range wards, flash some slightly bigger walls than you'd expect, and yeah thresh lanterns at a slightly longer range than expected, along with various other things I cant think of off the top of my head.
Of course, theres plenty of fail wards/fail flashes/fail lanterns that can come from trying this sort of thing, so practicing in the practice tool is a good plan.
I'm fairly sure it's all intended behaviour.