Attempto Controlled English[1] is a cool project: it's a formal language, but a subset of ordinary English.

My own Hode, described in an earlier comment[2], makes it easy for anyone who speaks some natural language to enter and query arbitrary structured data.

[1] https://en.wikipedia.org/wiki/Attempto_Controlled_English

[2] https://news.ycombinator.com/item?id=21784617