Or wait, no, that line wasn’t the issue, because it wasn’t an *if clause… it was just text displaying…
Let’s see, line 11 was here…
And that’s where it would be trying to set mytest2 to match “there are three things here.” So that’s where it was.
I’m not sure about the brackets here 
I think I’d be used to something like *set mytest2 “${mytest}”
But then that same line appears to work in your new version
I guess it’s working because you’d set mytest to become “three” rather than “there are three things here,” and it also worked because you’d created "three as a temporary variable. So that’s the difference here.
I’m just not sure why it works with plain brackets, which I don’t think I generally see in code… is there a change in how coding works with brackets for variables, or is this unintended behavior?
Edit: Wait, I see, this bracket use is a feature described here: New ChoiceScript features for programmers
That does make things smoother 
(And is indeed in the Advanced Choicescript Commands page under “Curly parens” and “Set by reference”… there we go. I think I’ve just been used to seeing it the other way around 
)