Sahih International English Qur'an adds words ... Not in the Arabic Qur'an. Why?

English translation of the Qur'an is different than the Arabic version. What is the agenda? Is it because the Arabic version can't be hijacked or altered? There are thousands of Muslims who have the Qur'an memorized in Arabic. They would notice. They could restore the confiscated and burned ones. But are they keeping sentinel elsewhere? Who runs qualify control on the translations? That is where the Shaitan's minion can steal power from the individuals in the ummah. Allah's power will stop at the prophet if the English translations keep inserting (Oh Mohammad) after the word "say". (kul) my understanding is that the Holy Qur'an came through the messenger, to the people. But apparently, the English translations (at least) are being subverted. Any thoughts?