By using the SugarApp from the offical AppStore (iOS) the App went into an "internal error".
I was able to locate the problem by checking the App's Log:
[ERROR] FATAL[2019-10-10 12:16:28]: The quota has been exceeded.
The problem always occurs when adding Opportunities to the list of shown modules.
The reason is that opportunities are having a lot of app_list_string's in our system.
The transfered lang_de_DE_mobile_ordered.json file has a size of 6MB.
Because the app is using the local storage of the mobile device and the maximum of an iOS device is 10MB, we're running into the limit.
Is there any possibility to fix this issue without reducing the app_list_strings?