I'm... Sort of of two minds about it? It's not a scenario I've specifically put thought towards.
On one hand, I do feel like the way we treat sex/nudity as inherently, and uniquely, traumatic isn't exactly... Great, in a lot of ways. Like. I walked in on my uncle watching porn once when I was 5 or 6, and it wasn't a traumatic experience. I only remember it because of how the adults around me reacted when I said something.
On the other hand, if the kids are young enough, they won't have a clue what's going on in the other room from noise alone. As they hit their teenage years they 100% will, and they will put two and two together about the past noises they heard.
On the other other hand, an adult in a room mate situation can put a restriction on sex while they're home, specifically because they can know when that's happening. The kid can't, specifically because they don't know.
There's also the consideration of "This is a minor" that I haven't even touched on. Ethics aside, there could be legal ramifications.
Idk my gut feeling on this is "Maybe we should be waiting for while the kids are at school, or at the grand's, if we can't keep it down during sex," but also idk if that's an actual ethical decision I've come to on my own, or if it's just how I've been raised, and the society we live it.
Thank you for posing the question, though. It's something to chew on