@Fabian697 I think I would make it even clearer in your listing that you sleep in the living room when you have a guest and confirm in your booking message that they understand that's what's happening. Definitely not saying it's your fault that guests don't read, but they don't, and your arrangement is a bit unusual. Things don't always translate all that well either (Google Translate is fickle), so it's best to be extremely clear. Also, maybe clear up what you mean about usually being in your room. If you have a guest, do you also use the room if they're out? If not, I would change that wording, because it may put some people off booking with you.
As for these guests, I would bet that they just didn't take time to read the listing, or one of them booked then the other wasn't happy with what they chose. I think your refund was fair, and I would just leave it at that.