Some thoughts --

First, even if we assume a totally static type-subtype situation, the dichotomy for Narrator/Taciturn would be very clear only for the split subtypes. For Diana, for example -- she's clearly Fi subtype of either ISFj or INFj IMO, and that would be enough to blur the dichotomy.

Second, if we assume the "floating" type conception of Smilingeyes, what is relevant is not so much whether one is consistently a narrator or taciturn, but, in the case of eg INTj, whether one is consistently narrator-positive and taciturn-negative, rather than narrator-negative and taciturn-positive.