About climax scenes :
It's honestly extremely hard and time consumming to make (and most of the time it doesn't look really clean). and it's also the part I find the less fun to animate mostly since it takes so much time.
If you want an idea, simply making the climax part for the second Nemona scene took me twice as much time as making both the animations before. (I was still pretty bad at animating at the time so I'm sure I could do better now but the order ofsize would stay about the same)
So that's why I was sort of slowly taking the part of not animating them anymore and just having an image of it so I could go a bit more crazy with how the cum splattered and all that.
It does indeed take the longest, but I think it's good to look at how many developers spend that extra time to really do it well, because it really is the climax of the scene, in multiple ways haha. It's a porn game in the end, and I personally think (and I know a good chunk of devs would agree) that sacrificing quality on this in particular, is probably not where you want to save your time. I do of course have a bias, but this truly is what I've observed, also from player feedback. The more you do it, the faster it will go as well—practice saves you time in the long run, and I'm sure you've already felt that!
(Just know that I've already done a few scene for next update and they have freeze frame climax so don't be too disapointed for those)
I'm afraid I can't promise that haha, because for me personally, it ruins the scene. Like lighting a firework, seeing it shoot up into the sky, then the camera cuts to black, and cuts back once the firework is already gone. That's how I feel about it
As for sound design, it's really hard to do or find appropriate sounds without ripping stuff so yeah I can't promise you anything on that side.
It can be difficult, but try searching Google for stuff like "F95Zone sex SFX" and you'll get results like
this (that's just an example). I think it's a good idea to look at how many developers really go out of their way to get good SFX in there, and then ask yourself why they would spare the effort. I think you'd agree it's because of my previously mentioned reasons, of it really adding a ton to the scene and making it much better overall. Don't forget the experience of the user is very different from the developer who knows the inner workings, and exactly what is happening. Visual/audio cues are perfect to give "player feedback" as it's called, to indicate something is happening. (In this case, your protagonist is cumming in someone or whatever, and the visual and audio feedback really helps selling that, increasing player enjoyment by a huge margin comparatively.)