VID-1841 Make sure cat names use underscores

:+1: And that's fair, I could see how transformCatNames could be interpreted as changing values in place, as opposed to changing and returning. Since changing these underbars to spaces is pretty trivial, I think I'll leave it as is right now. If that functionality turns out to be used in a lot of other places in the code base, at that point we could take it out and make it more general. Either way, thanks for the feedback, I appreciate it!