I actually liked the mixed language approach (keywords/library functions in english, my stuff localized) when I've learned programming (and did not speak english well):
Even then, you can learn the keywords and standard library function names easily - but to name things, that needs a different level of language knowledge.
So teaching in mixed languages is a good compromise. And it is also very helpful to immediately distinguish between things that were already there, and things have been defined in the actual program. I remember this being a helpful feature to learn language/stdlib by simply reading others code.
The more I think of it: it would be good to get back this kind of easy differentiation (maybe with IDE extension?) now...
On the other hand Scratch have localization support, and lack of syntax errors - maybe the two largest blockers for smaller children...
