Earlier quoted context omitted.
Wikipedia uses a “文A” icon; IMHO far better than a flag. What flag would you expect to see? As for finding the language in the menu, listening a language in the foreign language seems like bad design too. The menu should list “English” as an option! See: https://en.m.wikipedia.org/wiki/Language#/languages
I personally had no idea that icon let you change the language of articles (a concept I explicitly looked for before). Still confused at what the icon is actually supposed to mean.
It's also been used in the Google Translate logo as well.
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[0] https://en.wiktionary.org/wiki/%E6%96%87
[1] Not only because of Simplified/Traditional/Japanese renderings (文 is mostly the same across all three), but more strokes for a small icon is a bad idea regardless