Steam itself doesn't censor anything. (Also it's "censor", not "censur".)
Any content-changing decisions are made by the developer and/or publisher. Sometimes some of them make such decisions; sometimes others don't. It's kinda inconsistent and you have to take it on a case by case basis.
Steam is actually kinda the high-profile and convenient place to legally get at least a good handful of high-profile VNs in English these days. Which is a pretty big surprise if you look back about 8 years to what Steam was back then.
Which is a good thing I guess. I'm happy for VN devs and VN fans, though I'm not much into VNs personally.
(I'm also not a huge fan of having everything on Steam, and prefer DRM-free releases because they give me more flexibility as to how and when I can access them.)