To me, this word is so unusual that it's non-existent. But that's not so uncommon for a whole raft of adjectives that lie in wait for some special meaning to arise so that they can spring to life and become usual.
I just googled it and found that the number of hits illustrate that it is in use for some, in certain circumstances.
Results 1 - 10 of about 46,400 English pages for "the founded".
Joe, there's one I found in a bill from NH;
"This bill requires founded reports of child abuse and neglect to be listed in the central registry and establishes a procedure for individuals to petition to have their names removed from the registry."
http://www.gencourt.state.nh.us/legislation/2002/sb0409.html
Also founded constructions, founded framework, founded documents. All Greek to me.