That’s just partly true. While non-native speakers obviously recognize that something is a swear word, without immersion it’s often hard to gauge how it will be perceived by native speakers, simply because you don’t meet many, or any, to get reactions from.

I’m a non native speaker and it wasn’t until University when I met actual Americans that I realized my swearing could be ear-curling from time to time — I simply hadn’t noticed the reaction I got before in my life.

A simple example is the Swedish word “skit” and the English “shit”. In Swedish it’s actually pretty benign, for different reasons it’s not at all at the top of our swearing hierarchy: if you’d use “shit” in English in the same situations as you’d use “skit” in Swedish, English people will react.

So both in cases where there are cognates and a lack of actual experience with native speakers, there’s definitely a disconnect. I think any native speakers who have met good non native speakers have experienced this, they have 80-90% down but lack the cultural context (because where would it come from, movies isn’t enough)

As a Norwegian, we also have swear words that are not that bad. The problem is that the closest translation is often "fuck". So if you meet a Norwegian, don't be surprised if they drop the f-bomb frequently in business meetings. Many are not aware of the social context.

UK has git, sod, bastard, shit, tosser etc. Which you would use at work depends on work culture of course.

For me, it is not so much that I am not aware. I am aware.

But, when you swear in my language, I am bothered by it. It feels rude. Swearing in foreign language does not bother me at all. It does not feel rude.