There are only 7 households in my housing complex.
It is a housing complex where people who want to reside there form a union, participate in the planning and building, and essentially become business owners.
ご質問ありがとうございます。
「私の住む集合住宅は7世帯しかない」は英語で「There are only 7 households in my housing complex.」と言えます。
コーポラティブハウスは英語でそのまま「Co-operative house」と言えます。
もし、「Co-operative house」の説明もしたいなら、「It is a housing complex where people who want to reside there form a union, participate in the planning and building, and essentially become business owners.」と言えます。
ご参考になれば幸いです。