I think it's technically true that someone in China at one point used Esperanto to introduce Western languages to a few other people, because around 1900 it was part of a package of futuristic Western ideas like overthrowing the Emperor and Communism.

But the claim omits how utterly unsuccessful Chinese Esperantists were at their goal compared to the revolutionary Communists. (Even though they were sometimes the same people, e.g. https://en.wikipedia.org/wiki/Hu_Yuzhi )

For comparison, a few years after Zamenhof started Esperanto, Paul von Möllendorf (a German aristocrat working as a customs official in Shanghai) suggested in his Manchu grammar https://en.wikisource.org/wiki/A_Manchu_Grammar that Westerners should study Manchu as an easier introduction to the Chinese classics, the Chinese Emperor at the time being ethnically Manchu. Then the Emperor got deposed and by now the last native Manchu speakers have probably all died of old age. Learning Manchu in order to learn Chinese would be a collosal waste of time.

Chinese Esperantists that I know don't really seem to make fewer or different mistakes when using Esperanto than when using English. The marking of tenses with -is, -as, -os may be perfectly regular, but that doesn't help much when grammatical tense itself is a foreign concept to you. Someone who usually uses present tense in English when talking about the past will tend to also use present tense in Esperanto when talking about the past.