You still would have to translate the entries yourself. If you go to batch translate and select the source (in which you have the translation) and target (where the field is empty), you will find an empty field on the spot where the translation should be.
Like you see here
Hi there. Did you manage to find a solution on your problem? Because i’m facing the same issue and i can’t resolve it.
See the documentation here: https://docs.mendix.com/refguide/translatable-texts/#4-setting-the-end-users-language and the two options you have to change the user language. In your case use the second method where your force Mendix to reload the page.