By default, the described problem is due to the fact that the language is not set the same in the web account and in the app. One solution is for the member to briefly change the language in the app to another language and then immediately change it back to the desired language. The language is then saved and synchronized in the account and in the app. 

Note that any booking information defined in the class settings is not language dependent. For multilingual information it is recommended to write the translation among each other.
For example:

DE: Please wait in the marked area.

FR: Merci d'attendre dans la zone désignée.