An overall summary assessment of the current status of the relative strengths and limits of empirical foundations and theoretical assumptions and philosophy on which affect/script theory is based has been written by the social psychologist M. Brewster Smith, a friend and colleague of Tomkins for about half a century. Smith's comments can be found as the Introduction (pp. 1-12) to a book of essays by and about Silvan Tomkins titled EXPLORING AFFECT: THE SELECTED WRITINGS OF SILVAN S. TOMKINS (Cambridge University Press, 1995), edited by E. Virgina Demos of Harvard Medical School.
In regard to your specific question, Smith wrote "As for his [Tomkins's] attempt to base the distinctions among the affects on different patterns of neural firing, these speculations look harder to test...I don't believe they [the distinctions based on hypothesized neural firing patterns] matter much..." Smith does think identifying the basic affects matters, of course, and he especially thinks script theory matters a great deal. Affect/script theory is not a finished product; many of its aspects remain to be worked through.
Unlike Smith, I think the distinctions between affects based on hypothetical nerual patterns of stimulation do matter, however. But I understand the distinctions, for now, to be essentially theoretical constructs serving with unusually good efficiency to conceptually organize observations and relationships among the innate six affects (interest, enjoyment, distress, anger, fear, and surprise). Shame, disgust and dissmell are strictly speaking not regarded as affects (but as affect or drive auxiliaries) because their presence is not directly triggered by hypothetical neural stimulation patterns.