The bit about finding reading/writing Swedish porn kind of weird is really interesting to me! Because yeah, "cock" does seem like a perfectly natural English word because it's used so often in English fic porn, and I'm so incredibly grateful that there's any word for genitalia that's become essentially invisible to me; the rest of what you're describing (all the words you could use seeming clinical, childish, coarse, etc) is very true of me for most other English words, and it took a long time for me to stop feeling like porn-writing was inherently super awkward and silly. I'm not surprised that it's also a potential difficulty in other languages, but it's really cool to hear :)