Hello out there,
This topic is quite interesting, because it discusses an very old controversy using different languages in science. A little bit history in short...

In Antique, it started from the Romans using old-Greek for education of their children and for the language of science. As the Empire grew, old-Greek was replaced by Latin. This ancient language survived over centuries, because it was
the communication tool between the scientists. Not 200 years ago, scientific work was still published in Latin, but theories and research were developed by the researchers and philosophers in English, German, Italian etc. and translated to the main language. This role of global language for science, is English nowadays. So, there have been reasons for using one language... it accelerated the growth of knowledge.
Conclusion and my wishes for CZ:
1. Internationalization of CZ should be implemented by translation of articles. There is one truth, (but I know, there's billions of subjects looking at it). Who's capable to write in English should write, and who's not should write in his own language.
2. Using different domains for different languages like WP do, will not be applicable. It is not effective building own institutions etc for maintaining one language. To my opinion, the main problem is tracking changes between languages. English should be the main page of an article and - vertically not horizontally like in WP - should be all other languages. A tool should organize and track all changes compared to English and of course back to other languages. Maybe for the initial translation a bot will be O.k. and the page marked as translated by bot... (sorry, too much details...)
3. Like someone said earlier, material differences between languages should be explained in article itself. That's what a good article should do anyway, if proper researched.
4. And finally, I hope, in five years, I will be able to do my research with a confidential source using CZ in any language I want.
Thank you for reading this post.
Regards
Dejan Stojanovic, Switzerland