This is a thing I forgot indeed :(. Right now you only have access to the actors of the current level, but since the hero is jumping through the levels, there might indeed be a problem that you cannot access the actors of different levels.
It was indeed the intention that in the on-hurt, you can access everything like in other scripts (an oversight on my part).
Added as a critical bug at: https://trello.com/c/cOinI43A