My intent is to translate “labels” on columns - not the fields themselves (I always use English for code & db stuff, even though I am not native speaker). If I have a German user, I want to have Benutzername instead of Username - for example. This is all.
In edit view, if I use a label user_username and have that string defined in my translation fields - that is used, but for column names not. Probably just the case that i18n logic is not used for column names - for now. If so, it would be quite easy to implement this with just a formatMessage call for each column.
So - this question if NOT for the content but purely for UI. This way German user has UI in german and can have content in whatever language it wants, as well as English user.
The current situation leads mixed languages since parts of the UI can not be translated to user’s preferred language.