original: It was to serve as an international auxiliary language, that is, as a universal second language, not to replace ethnic languages.
simplifications: it was to be an extra second language, not replace the traditional language. It was to serve as a universal second language, not to replace ethnic languages. It was to serve as an auxiliary language. A universal second language. Not to replace ethnic languages. It was meant to be a universal second language. It was not meant to replace ethnic languages. It was to serve as an international auxiliary language. It is a universal second language. It is not to replace ethnic languages. It was meant to be an international secondary language that would not replace ethnic languages. It was to serve as a universal second language, not to replace ethnic languages. It was to serve as a language that was used everywhere in the workd, but not to replace ethnic languages. It was an international auxiliary language. It was a universal second language that was not to replace ethnic languages. It was to serve as a universal second language, not to replace ethnic languages.