Sérac@serac@troet.cafe
@FediTips@social.growyourown.services
Seems like this feature only works if you publish everything in the same language. There is no apparent way to define a language for every posting individually (where the auto detect would become really handy).
Fedi.Tips@FediTips@social.growyourown.services
@serac@troet.cafe
There is, if you're using the web interface or an app that supports selecting the language.
For example the official iPhone app has a button at the bottom of the post with the language code on it, you can click this to change the language just for that post.