Reading the Bible this week I found another 'insertion' in the NWT that doesn't even have the [] around it, and I'm looking at a NWT that DOES still use [] for inserted text.
It's at Rom 16:7
NWT - Greet An·dron'i·cus and Ju'ni·as my relatives and my fellow captives, who are men of note among the apostles and who have been in union with Christ longer than I have.
This makes Junias a male apostle, but it is a womans name.
Other renderings:
KJV - Salute Andronicus and Iunia my kinsmen, and my fellow prisoners, who are of note among the Apostles, who also were in Christ before me.
Revised - Salute Andronicus and Junias, my kinsmen, and my fellow–prisoners, who are of note among the apostles, who also have been in Christ before me.
Douay - Salute Andronicus and Junias, my kinsmen and fellow prisoners: who are of note among the apostles, who also were in Christ before me.
ASV - Salute Andronicus and Junias, my kinsmen, and my fellow-prisoners, who are of note among the apostles, who also have been in Christ before me.
In fact in the 17 versions I have checked, only the NWT includes the gender 'men', to support their teaching that no women could have any positions in the congregation.
Splash