- the name is bad. Issen? I (German, Spanish speaker) don't know how to pronounce it.
- use correct flags. Catalan speakers will be rightfully pissed when you use the Spanish flag for their language.
- in a language learning focused app, it is not acceptable to have a badly translated app. I'm using it in German and while the intro does not have typos, I can tell it's all just AI blubber
- For German specifically, I'd recommend you to use "du" and not "Sie" ("Wie heißen Sie?") across the app. If your tool isn't aimed at 60+ year old BMW drivers, use "du".