I honestly think the child would be far better served with Scratch rather than some half-assed adventure writing language (having created several such languages myself).
Edit: To clarify, the languages I created were also half-assed - it's very difficult to create a good one.
I think the only thing that matters is whatever the kid finds appealing enough to do at all.
Scratch is so bad I think it must put kids off.
It makes zero sense to start people off in an actually bad programming environment.
Try Snap! Instead of Scratch.
I'd say Canon and Scratch are different tools with different purposes. Both are simple and interactive enough for children to love. The main difference I see is that Canon abstracts away a lot of the game state management logic and you get to focus on creating characters, items and having lots of fun. Scratch looks like it has a steeper learning curve and while it is a good introduction to programming, it gets pretty hard to navigate once project size increases. As someone who started programming with Scratch, I think that making a text adventure game like the ones Canon does in Scratch would be much more complicated and the end result wouldn't be half as nice.