[hawkice]

Mandarin Chinese is a curious example of this because it's at an almost perfect intersection of constructed and natural (which aren't opposites). It was defined as the language spoken in Beijing but limited to the vocabulary shared between all the Chinese languages. Which is not a language anyone was technically speaking at the time -- Beijing slang was and is pretty common -- and we can confirm it was constructed because we know who, when, and where Standard Chinese began. But it is still obviously a natural language.

Simplified Characters are another example. A lot of the simplifications had been around for a very long time, so they existed as part of a natural language, but saying, X is traditional, Y is simplified, and standardizing the simplified version, is fundamentally the act of language construction. [The lack of such a deep history is probably why https://en.wikipedia.org/wiki/Second_round_of_simplified_Chi... never caught on.]