This isn't Nightmare on Elm Street or the Matrix. In a perception, something is percieved (obviously), if what is percieved is not real, the perception is an illusion.
You are still missing the point. Even if the perception is an illusion which does not represent any actual spacio-temporal object, that illusion is still real.
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I have seen all things that are done under the sun; all is vanity and a chase after wind.