Iconography already exists for that. On Windows, it’s a symbol comprising an A and a 文. On Apple systems, it’s a globe icon. I think the globe icon is seen more

Iconography already exists for that. On Windows, it’s a symbol comprising an A and a 文. On Apple systems, it’s a globe icon. I think the globe icon is seen more often on other platforms and on websites. Having the localised language name next to the icon helps, too.