The "me.parent.widgets" thing is a mix of my understanding of the namespacing still being a little fuzzy, and also probably me just trying anything I could think of.
In any case: you were correct, re: converting to a number. That sparked off a memory of wondering why there was a "+0" in the "get_value" function in the counter example from the docs, and it seems the answer is that's the quickest way to make sure the text casts to a number. Once I did the same with the result of "answer", the widget works as intended now.
Thanks!