Can’t comment on Korean, but Japanese beginners worry far too much about politeness. It doesn’t help that the textbooks all start with a relatively stiff level of grammar, but Japanese students often become neurotic about it.

If you’re a beginner, no reasonable human being is going to think anything nuanced about your choice of words. When was the last time you judged a non-native speaker of your own language for this level of subtlety?

My advice is to do whatever it takes to be understood. You’re going to sound like a rude idiot. Make peace with it.

You are totally right. This is why I don’t even bother using polite form expect when I really need it: my interlocutor is glad I’m speaking more Japanese than he could speak English or my native language anyway.

I would also add that speaking a Japanese that is too good can backfire, as native have then more expectations that go further than language (behavior), especially for East-Asian people. Keeping illusion of semi-(in)competence can be useful.

> There as elsewhere foreigners are held to higher standards.

I've found the reverse in Korea: the tyranny of low expectations. Often Koreans simply refuse to speak to me in any way, saying even a single word beyond, "I don't speak English".