Yes, God is omniscient, but we live in a fallen evil world. God did not translate the scriptures from the original God-breathed text into all the versions that we have today. Men did that. Some of those men had agendas so they twisted the original language to suit their agendas. The biggest agenda was to control people, especially women. God did not change scripture. Men did. This is serious evil done by men, not God.
Revelation 22:18-19: (NIV)
18 I warn everyone who hears the words of the prophecy of this scroll: If anyone adds anything to them, God will add to that person the plagues described in this scroll. 19 And if anyone takes words away from this scroll of prophecy, God will take away from that person any share in the tree of life and in the Holy City, which are described in this scroll.