At this point, I don't think there is anything simple you can do for translations in Android. Some of the translations are loaded outside of app context, and app developers may not know which ones those are. Allowing the files to be compressed in the apk would require support in the Android system, and there are a billion devices already shipped that don't know how to do that.

If you can tell what strings need to be in the old way and what can be done differently, you could do any number of easy things to compress the strings that don't need to be accessible by the system.