I don't see this as being a problem. Show me one quote from any of the Apacryphal books used by an Apostle anywhere in the NT. It's a large leap of logic to say because they quoted the Septuagint in one place that they gave all the book contained therin blanket admonition as official OT. OT Conon are those books written by a prophet or during the time of a prophet. It's a simple concept really.
First off, how do you know the authorship and time frame of each of the OT books? You argue as if you have absolute knowledge, when I don't think anybody knows for sure the authorship of all the books.
Second, what is a "prophet?" Isn't it someone who speaks for God, delivers God's message to the world?
Then your argument is circular and self-defeating. If the authors of what you call the "Apocrypha" were truly inspired, then they were "prophets" and they obviously then lived during the "time of a prophet." It's tautological.
SD