Is your phone rooted?
If so you can try game cih. You might have to go in and edit its name due to many apps blocking it now adays. If you need help on it that just ask. Cih is just like cheat engine for your android though so you should be able to do that easily. Or your can always reverse the app and then make your own ways to add coins if cih wont work for you. Thats a whole lot more complicated though.