Quick question: Can “ferre” be used in the sense of “bearing witness to”?
I would say no, but it depends on the context. The Romans have a deponent verb, testor, which does what you want. ferre means literally to carry, and often to relate, but it seems to me that ‘to bear witness’ is too idiomatic to be able to use ferre.
With the access, notion of publicity, to make public, to disclose, show, exhibit …to show, manifest, to let be seen, to declare …
Of speech, to report, relate, make known, assert, celebrate …they relate, tell, say; it is said, it appears , etc…To give out, to pass off a person or thing by any name or for any thing; and, in the pass., to pass for any thing, to pass current…set himself up for, boast,…boasting of ,…to bring forward or move a proposition, to propose a law , etc…to offer or propose to the defendant as judge : quem ego si ferrem judicem, refugere non deberet, Cic. Rosc. Com. 15, 45 ; id. de Or. 2, 70, 285.–Hence, judicem alicui, in gen., to propose a judge to, i. e. to bring a suit against, to sue a person: se iterum ac saepius judicem illi ferre, Liv. 3, 57, 5 ; 3, 24, 5; 8, 33, 8.–
http://old.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3Atext%3A1999.04.0059%3Aentry%3D%2317965 Sensus anglicè “to bear on/out” non longè ab eo quem quaeris, ut opinor, etsi non ille ipse.