Contents of the contributions will always have to be in english.
Thank God, at last, I mean yeah, contributions of any language were nice for spreading the word, but might have been a pain in the ass for quality control. I can understand if you'd trade accessibility for better QA.
English is universal, and translating English to regional language is much easier for the user who would want to read the tutorials. So I believe this is a good move to make only English.