Why not: They made that house their own?
Sounds like a valid translation to me. Report it
I, too, translated this "They made that house their own." It was marked incorrect.
The original sentence doesn't sound very natural. Mereka menjadikan rumah itu... suggests they gave the house a 'function', e.g. kos/ sebagai sekolah / etc.
i agree that "They made that house their own" should be accepted as correct. That is how we would say it in Australia!