My app works in a bring your own content kind of way. Most users AI generate their expressions, which gets you pretty far, especially in the beginning. But for languages I speak, I curate my expressions with things I read or hear or get corrected on.

I've also tried to use a more sentence-mining approach for Japanese, given the cultural differences, but tbh I haven't found much benefit at my level (A1/JLPT5).

I'm pretty sure it's impossible to avoid awkward situations in other languages, 10x so with culturally foreign languages. Best I can do is help you learn from them :)