Speaking from experience, it really doesn't feel any different from translating SFW stuff. But that's coming from someone who enjoys reading NSFW comics in the first place. If you're squeamish about reading them in the first place, yeah, it's going to be hard I guess. I don't recommend taking on projects that make you uncomfortable.
What do you think of this old man's penis, Nene-chan? Impressive, isn't it?This is the dick that's about to be churning inside your freshly-debuted pussy~
Now now, look this way, you've got to keep your eye on the prize~Ahhh, she's so afraid she won't even let out a single peep. How cute...