Don't think that's the correct way,did you replace those folders on xiaomi.eu Rom zip and then flashed again?other way it will never boot.
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If you don't know how to do that you can still have it this way:
Flash miuipro Rom, "enable it", come back and flash xiaomi.eu Rom again (dirty) it will be still there.
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By wiping data doesn't erase the internal memory but apps&data.(Erase or format does). Anyway to downgrade you can try by wiping just Dalvik/&cache probably no issue.
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