1. What was the esperanto experiment and why did it fail?
Esperanto was created during the 1870-80's and first published by L. L. Zamenhof in 1887. Languages Zamenhof spoke included his native languages of Belarusian and Yiddish, with later additions of German, French, Latin, Greek, Hebrew, English, and awareness of Italian, Spanish and Lithuanian. Zamenhof felt that many of the conflicts between different nationalities or cultural groups could be traced to the communication difficulties caused by language differences. Esperanto was his attempt to create an international language.
Esperanto has continued as a "constructed international auxiliary language" since its publication. It has not been recognition as an official language of any country, but it does have a growing number of users around the world.
Esperanto is a language. It is not an experiment. I have been speaking Esperanto during 52 years, and it never failed me.
Even if Esperanto falls in the "Constructed Languages" category, I would use the word "planned" instead of "constructed".
Because it is planned, Esperanto is better structured than other languages, and much easier to learn.