Cool idea, but the editor is not open source or at least not usable locally as far as I can tell, so that's a no go for me. IMO, I'd rather just use unity or godot.
I think this looks like a good way to teach a teen using minecraft. It is windows 10 based though, and doesn't look to use an actual programming language, but does provide a good way of learning the fundamentals that most languages do have.
https://makecode.com/blog/minecraft/10-18-2017
After they make it through that you could transition them to learning java and making minecraft mods which should be interesting enough. Personally, I think having access to google/stack overflow is a must when learning a language, not being able to ask or find answers to questions can be a huge turn off for newer programmers and may make them want to give up.