i was ilustrating that the claim is pointless - the ignorance can sit on either side of the problem, depending on which of the above described PoV you chose to adhere too.
you have something that behaves like Fi, and if you choose to view functions as behavioral descriptions only, then it can be said that you have Fi, in which case my illustration would suggest i am ignorant to what Fi is simply because i am suggesting that the "Fi-like" behavior can stem from something else altogether, as in the first philosophy there's no question to what it stems from in the first place, and thus it wouldn't matter, there's no distinction between "Fi" and "Fi-like", since the likeness is the only criteria.
if you choose to take the (somewhat higher risk and more presumptuous) endeavor of thinking of functions as more then that, a.k.a. a more detailed phenomena then just the surface manifestation which has deeper cognitive origin, then the question of whether something is Fi or Fi-like but with a different origin, then the possibility you have something which acts like Fi but has alternative origins is likely.
such as the one i suggested, your version of Fi-like-behavior being "Fe in a box", or any other. the first version is more reliable, but the second version is a lot more interesting. for example, in myself i know that Fe+Si, can resemble Fi at times, but when examined deeper its very distinct from Fi, it's about feeling when there's a contrast with what is basically "habits[Si] of thoughtfulness[Fe]" rather then any deep seated moral sense of right and wrong. likewise, Ti+Ne can manifest in ways which resemble Ni without actually being Ni or carrying much of the implications that Ni has. in this manner, the exploration of function theory can become less metaphorical and a lot more meaningful.