You have very modern apps, web app has adaptive design, congrats on that. I really like how it looks and feels.
Still I would suggest to unify the user interfaces for showing/hiding translations:
- smartphone browser - swipe down, no way to discover it or I don't remember was it on intro
- desktop browser - press up, then click on pin, the instruction was in FAQ
- native app (android at least, I don't have iOS) - press an arrow