Dogen contradicts himself because he tries to show "all sides of the story". His teaching is a "pointing out" instruction that ANY viewpoint is simply that, perspectival knowing.
An important question then, is this,
if Dogen (and Nagarjuna) are claiming that there is no objective reality in our constructed world of concepts and language, is science being denied? Is fake news ok? Is this a position that basically accepts post modernism?
No, I would say no to all of these. It's pointing out the LIMITATIONS of concepts and language. They are incomplete and always leave with a sense of wanting more. And since Post Modernism is also one point of view, it is also thrown out by Dogen and Nagarjuna. Remember, ALL points of views are points of view. Fake news is also a point of view so those who practice it can also not justify it.
What Dogen and Nagarjuna are saying is that as soon as one enters the world of concepts and language, any concept and anything side is inherently one sided. It is inherently perspectival and situated in an inherently incomplete conceptual space.
As Tibetan doctor/monk Barry Kerzin points out in this conversation with physicist Carlo Rovelli, there is a critical difference between "existence" and "intrinsic existence". The first is not being denied by Nagarjuna, but the second, intrinsic existence, the existence of concepts and the words that represent them, is. If these two are confused, it can lead straight to nihilism.
https://hyp.is/go?url=http%3A%2F%2Fdocdrop.org%2Fvideo%2FsPSMTNjwHZw%2F&group=world
This also aligns with John Vervaeke's perspectival and propositional knowing in his 4 P ways of knowing about reality: Propositional, Perspectival, Participatory and Procedural. A good explanation of Vervaeke's 4Ps is here:
https://hyp.is/go?url=http%3A%2F%2Fdocdrop.org%2Fvideo%2FGyx5tyFttfA%2F&group=world