I find this really strange. Of course only Greek witnesses count, because translations cannot be trusted with such Graecisms as "monogenes theos".You are confused. I said you were wrong in claiming only Greek mss. count. Raymond Brown does not say so.
From my studies, Irenaeus, Origen and Clement of Alexandria are all mixed witnesses. You might want to do your own checking before using quotes. Your last quote of this nature had about five errors.