I have been working to get the in-app language switching feature implemented in this project for some time. The simplest way I found of implementing this is to have a preferences window which allows the user to select which language to run in the app. I incorporated the preference window and language switching selectors into the app. However, implementing the language change into the app I found nearly insoluble. When working with other programmers I ran against a brick wall. I contacted tech help at Gospel Library (LDSTech) about how to perform a language switch and they said it could be done but that they could not share how this was done due to copyright issues. I then took this issue to other professional programmers who gave me the code needed to make this feature work. I used several different methods they gave me but kept running into errors for every single method know. In addition I kept being warned by the professionals that the code they gave me should not be used for market/end-user applications! I have no idea how Gospel Library changes the language in their app and since they cannot tell me, due to copyright issues, I do not feel safe publishing the app with this type of undocumented API.
For those still interested in the language switching feature, I have put the app with all the language changes in a zipped folder on Google Drive. If anyone knows how to implement the in-app language switching this would give you the best head start, because much of the content for in-app language switching is already present.