Huh. I agree with this actually. That's really weird.
Well. About it not being that subjective anyway, on some level, with you saying it's no more subjective than other IEs except Se. In the non-typological-pseudoscience-specific layman's understanding of "subjective" aka most of the world's.
As for "inward", I think "inward derived" rather than "inward oriented" is an idea I'd accept. Experiencing Ni is still subjective and derived from an internally-created interpretation of perception. An analogy would be like Ni is the neurons forming connections to Se's nerve/sensoric experience. It's the dual IE to Se and that's how the dual IEs work in connection in this case. Actually it's more or less really what it is too or is at least a large part of it, it's hardly even an analogy. I'm not a cognitive scientist but based on what I do know about the subject and the descriptions of these IEs if we were to take them seriously, there's really nothing else that it could be. Like it doesn't work by magic.