I know you mentioned about the apps, and I apologize if I'm going to be suggesting an app lol, but this one seemed to be useful for my friends who wanted to practice other languages:
HelloTalk-Learn Languages Free - Android Apps on Google Play It's called HelloTalk, and it helps you look for people who are interested in your language, so you can teach them, but likewise, they also narrow it down to people who are proficient in the language you want to learn, so it's a pretty good exchange in knowledge.