Honorific error : "~요"(해요체) is honorific but "네" is not. It could sound hilarious
It should be either casual form: "네 거실은 얼마나 커? " polite form: "거실은 얼마나 커요? "
I really wish Duolingo would pronounce 네 as 니 as most Korean people so commonly do nowadays
I've never heard of a lounge as a room in a home. I've only heard of some kind of chair being a scheiß lounge or something.
A lounge is a room in a hotel, airport, theatre, etc. where people can relax or wait. A living room is a living space in a house often where you have your sofa, TV and sometimes the dinner table.