The phrase "a far more authentic" is correct and usable in written English.
It can be used when comparing the authenticity of two or more things, emphasizing that one is significantly more authentic than the other.
Example: "This version of the painting is a far more authentic representation of the artist's style than the replica."
Alternatives: "much more genuine" or "significantly more real."
Indeed, Done Forever reveals that singer Elizabeth Sankey has a far more authentic soul voice than Florence, and a far more captivating rave-pop backing too.
But gross national income (GNI) can offer a far more authentic figure of Scotland's actual, domestic wealth because it counts the wealth kept within the country.
Unlike his main rivals for the nomination, Mitt Romney and Newt Gingrich, Mr. Santorum has held these kinds of views for many years, and is a far more authentic representative of the Republican Party's angry base.
Tour agencies in La Paz arrange white-knuckle mountain-bike trips down its length but, for me, the bus was a far more authentic way to sample the masochistic frisson of a route that has entered into backpacker folklore.
This form of assessment provides a far more authentic and comprehensive view of what students have actually achieved over the course of the school year than any standardized test possibly could.
The story suggested in that title card the retrospective reconstruction, at trial, of Herold's actions suggests a far more authentic, analytical film of life in the Wehrmacht as the country was falling apart than the foregrounded spectacle that Schwentke actually made.
The more you do things that are further from that, experiencing parts of life that aren't absolutely the industry, far more authentic kinds of activities, you feel like a person again.
Life from a distance seems beautiful; unblemished, perfect and seamless -- but life is far more authentic when up close, where we see the warts and blisters, where we see the cracks and stains, where we see the brokenness and the uncertainty.
Auditions would allow candidates to demonstrate their effectiveness in far more authentic ways than paper-and-pencil tests.
Vaccaro insisted that Cooke's shattered hoop dreams were far more authentic than those of William Gates and Arthur Agee, chronicled by the director of "Hoop Dreams," Steve James.
