Romans 3:9-15 is not a quote from Ecclesiastes, as you said it was.
It is a quote from Psalms.
It is not about Ecclesiastes, and never was. The passage has nothing to do with Ecclesiastes. Each and every one of those verses are direct quotes from verses found in the Psalms. That is what you will not admit. You have been wrong all this time, still are wrong, and refuse to admit it.
What is the matter?
You even question the many who translated the NIV 1984.
You are the one who is wrong.
I do not even need what those in the NIV referenced, because Ecclesiastes DOES explain to you what Paul said.