If the name of Cyrus was not inspired by God, but inserted by disciples of Isaiah, then God would have preserved copies of Isaiah without the name of Cyrus. But he did not. So the name of Cyrus is inspired. And it is not true that Isaiah did not write other names in prophecies. He wrote Immanuel. That name was not inserted by Christians, it is there in Jewish copies, even the Dead Sea scrolls. God preserved the Scriptures for us. It is true that sometimes scribes changed things, but in each case God preserved other copies with the correct wording. Otherwise we could not rely on the scriptures, we might as well give up and not use the Bible.
And concerning your claim that Isaiah meant the Church in Is. 43, no he didn't. Verse 1 says Jacob. The Church is never called Jacob. Verse 3 says "I gave Egypt for thy ransom, Ethiopia and Seba for thee". These 3 countries were later conquered by Cyrus. Ethiopia is really Kush in Hebrew, the land now called Nubia, nowadays divided between Egypt and Sudan, to the south of ancient Egypt. Notice that Philippines and other lands are not mentioned in verse 3, they were not conquered by Cyrus.