Ashley will look into these bugs, it's just that him and his team are mainly focusing on Construct 3 beta at the moment, so expect a delay. Plus, there is a bug with collisions that he is trying to work on as well. There is a blog on that issue on the website, so we just have to be patient. In the mean time, you can either just type out the entire expression or rename your objects to remove the underscore _ in them, because not having an underscore seems to be the best workaround at the moment until this is fixed. I love using the underscores in names and whatever, so I'll continue putting up with this until it's fixed.
Good work discovering that it's not just variables, though!