I have recently published an Android application on Google Play written in Python/Kivy. Normally the "build.py" script would wrap the whole project files into one single folder that is the application package folder. But if i check the content of this package on my phone after the installation of the apk i can find the "android.txt" file, the ".kv/.kv~" file and the ".py~"*and *"pyo" files.
My question is: is this safe to expose the source code files or is there something that i am missing in the compilation of my project ? What is annoying me more are the temporary files *.kv~ and .py~ that are exposing the whole project source code.*
But i should mention the gratitude and the respect i have for the Kivy project and the Kivy team. Their efforts allowed me to build and publish a nice Android application with Python that i am really proud of. Thank you so much Kivy team.
Those files may be editor backups which kivy doesn't recognize. 
You can edit the build.py and add some patterns to BLACKLIST_PATTERNS. For your issue, you should add '*~' to the black list.
How to hide python code file and other related files in a kivy project