I have examined more writings about interpretants by Peirce scholars, and the version by Short (excerpts below) is typical.  It's also consistent with the Stanford article by Atkin.

As Short writes, Peirce was "groping" for a definitive statement about interpretants, but he never developed a complete theory with precise definitions that remained consistent from one MS to another..

In a note to Gary R, I apologized for saying "RIP".  I now retract that apology.  Peirce never had a coherent theory of interpretants  He did make a three-way distinction, but he never stated reliable definitions that anybody else can use with confidence.

The last paragraph quoted below is as good as any and better than most.  Note Peirce's own words:  "The Normal Interpretant is the Genuine Interpretant, embracing all that the sign could reveal concerning the Object to a sufficiently penetrating mind..." 

That is too vague for guiding research on the many issues that Peirce discussed in the many MSS where he mentioned the word interpretant.  And it can only be used by "sufficiently penetrating minds".    I assume that he regarded his own mind as sufficiently penetrating.  But even he couldn't say anything more definitive.

John

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Excerpts from Peirce’s Theory of Signs by T. L. Short, Cambridge University Press, 2007.

Chapter 7, Objects and Interpretants, p. 178

In the 1900s, Peirce introduced several divisions of object and interpretant.  That was in an article, notebooks, letters, drafts of letters, and uncompleted manuscripts.  He was groping his way and never came to a definite, clearly articulated conclusion.  Much of this effort was directed toward providing principles for a sign taxonomy, developed in those same years.

We can see in that taxonomy (chapters 8 and 9) that he needed two quite different trichotomies of interpretant.  One, following from the teleological structure of semeiosis, pertains to each sign:  the immediate interpretant is a potentiality in which consists the sign’s interpretability; the dynamic interpretant is any interpretant actually formed (from zero to many); and the final interpretant is another potentiality, the ideal interpretant of that sign for the interpretative purpose.  The other trichotomy is an application of Peirce’s phaneroscopy and distinguishes among signs:  an emotional interpretant is a feeling or 1st; an energetic interpretant is an action or 2nd; and a logical interpretant is a 3rd, being a thought or other general sign or a habit formed or modified.  An immediate interpretant may be either emotional, energetic, or logical, and so also dynamic and final interpretants may be of any category, actually or potentially.  A sign’s final interpretant, for example, is that potential feeling or potential action or potential thought, habit-change, and so on, that would best satisfy the purpose of interpreting that sign.

The distinction between interpretants that are ultimate and those that are themselves signs, mentioned earlier (chapter 2, section 10, chapter 6, sections 6–9), is made within the class of logical interpretants and is [p 179] different from the two trichotomous divisions of interpretant, despite Peirce’s own occasional interchange of the similar terms ‘final’ and ‘ultimate’.  Thus, an interpretant may be final without being ultimate, and conversely.

Because of Peirce’s many changes of conception (especially of the final interpretant) and terminology, there has been much uncertainty about his divisions of interpretant and, in particular, a tendency among Peirce’s commentators to conflate distinct divisions (especially identifying the ultimate, the final, and the logical interpretants). To find our way out of these dark woods, we need to attend, first, to the different ways the respective divisions are defined.  They do not compete; they are made on entirely different grounds.  Second, we need to attend to the uses Peirce made of those divisions.  Both trichotomies are required in his sign taxonomy, while ultimate interpretants are required to complete the account of significance (as in the preceding chapter)....

[p 180] 1. Much Groping, No Conclusion

Before attempting a systematic exposition, let us review Peirce’s struggle with the divisions of the interpretant.  There is only one place, that I have found, where he named the emotional, energetic, and logical interpretants.  That was in the 1907 MS318 (primarily at 5.474–5), wherein he wished to focus on just the one type of interpretant named ‘logical’.  For that purpose, it was convenient to label the three alternatives.  Nevertheless, the trichotomy is clearly invoked, without benefit of labels, in other places and, especially, where the immediate/dynamic/final trichotomy is also invoked....

[p 181] None of the divisions is formally labeled here, but later in the same letter Peirce referred to immediate and dynamic objects and to immediate, dynamic, and ‘signified’ interpretants (8.335–9), leaving poor Lady Welby to guess which label goes with which definition.  Notice that the language used to describe the two objects, ‘[as] represented’ and ‘in itself’, is duplicated in describing two of the three interpretants, but with much less clarity of meaning.  Is it really the interpretant that is represented or to be understood?  And what determines how it is meant to be understood? Finally, what does ‘in itself’ mean when applied to interpretants? But 1904 is only the beginning of Peirce’s work on these distinctions.

The same kind of evidence for Peirce’s having intended two distinct trichotomies of interpretant may be found in his ‘Prolegomena to an Apology for Pragmaticism’, in the 1906 Monist.  Here, he first stated the emotional/energetic/logical trichotomy without labeling it as such and then, in the same paragraph, presented (for the first and only time in a published article) the other trichotomy, formally labeled....

[p 182] Whether the conception of the final interpretant was improved is another question; Peirce’s self-confessed ‘mist’ seems real.  There is much evidence, in unpublished manuscripts between 1904 and 1908, of a prolonged struggle with this idea.  In the October 8, 1905, entry in Peirce’s ‘Logic Notebook’ (MS339), the final interpretant is first named ‘significant’, but later in the same day, and in what appears to be one continuous act of writing, it is named ‘representative’ and is defined as representing the sign in respect to being a ‘Rheme [term], Proposition, [or] Argument’.  The next day, ‘ the Representative Interpretant is that which correctly represents the sign to be a Sign of its Object’.  The entry for October 12 is to like effect.  In the ‘Logic Notebook’ we witness Peirce thinking aloud, as it were.  He himself, in his entry of March 23, 1867, wrote, ‘Here I write but never after read what I have written for what I write is done in the process of forming a conception’.

The entry for April 2, 1906, is more helpful.  Now the final interpretant is named ‘normal’:

The Normal Interpretant is the Genuine Interpretant, embracing all that the sign could reveal concerning the Object to a sufficiently penetrating mind, being more than any possible mind, however penetrating, could conclude from it, since there is no end to the distinct conclusions that could be drawn concerning the Object from any Sign.  The Dynamic Interpretant is just what is drawn from the Sign by a given Individual Interpreter.  The Immediate Interpretant is the interpretant represented, explicitly or implicitly, in the sign itself....