They are very strict though on user contributions especially if it involves characters that belong to the devs, same with transformations those are strict there was a dude who made a 20 page elephant transformation + scenes but still got rejected even though it was pretty good.
FWIW, the main reason the elephant transformation item got axed was because the Devs polled the userbase about whether or not they would want it added to the game, and everyone pretty heavily said no. Size or quality of submission had nothing to do with it--people didn't really want it in/to take up time being coded if sex scenes, old and new, weren't going to explicitly call attention to the fact the PC-character had a trunk/could use a trunk during sex.
People gotta remember that the parser/engine the game is built around can only take into account so much, and that a lot of the stuff that doesn't really get touched on or put into the game--stuff like feet play; more centaur-centric or naga-centric scenes from the PC viewpoint; water sports; ovipositor scenes; etc--is because both the writing team doesn't enjoy it and freelancers don't submit it when submissions are open.
The best way to have content added to the game, if you want to write for it or have specific things show up, would be to just pick a prexisting character or encounter--and not one of the author's pet favorites--and either write a single scene you want to see, or comission someone to write it for you. (The former is what William, an author for both CoC2 and TiTs, did before they started to submit their own original content, and it's also what the writing post on the forum suggests new writers do if they want to see X or Y content in game.)
/end infodump