Nothing you wrote touched upon the question.  Why does spiritum principalem not suffice to signify the sacramental effect? That is the only question that matters at this point.

“The dispute hinges on the essential sacramental form for the episcopacy — the one sentence in the rite that contains what is necessary and sufficient to consecrate a true bishop. Put very simply, my argument was this:

 

• In his Apostolic Constitution Sacramentum Ordinis, Pius XII taught that a form for conferring Holy Orders must univocally (unambiguously) signify the sacramental effects: the power of the Order received (deacon, priest or bishop) and the grace of the Holy Ghost.

 

• In 1968 the post-Vatican II reformers completely changed the essential sacramental form for episcopal consecration. In the process, they removed one of these essential ideas: the power of Holy Orders (potestas Ordinis) that a bishop receives.

 

• According to the general principles of Catholic sacramental theology, if a sacramental form is changed in such a way as to remove an essential idea, the form becomes invalid.

 

• The new form, I therefore concluded, is invalid. Consequently, those consecrated with this rite are not true bishops.

 

A key point [no, the key point] of dispute in the debate concerned the meaning in the new form of the Latin phrase Spiritus principalis — rendered into English as “governing Spirit” and into French as “l’Esprit qui fait les chefs.”

 

Those who defended the validity of the new rite maintained that this expression unambiguously signified the episcopacy.

 

I demonstrated that it did not — I unearthed at least a dozen different meanings for it — and that in the new form itself, the expression means nothing more than the Holy Ghost, merely one of the required elements for a valid sacramental form for Holy Orders.

Your post was helpful in allowing us to drill down to the main point of the dispute, but it failed utterly in showing why “spiritus principalis” does not univocally to signify the sacramental effect.

What you did show is Fr. Cekada’s reason for believing why it does not, namely, because he looked up the definition of principalis and found that the word has more than one meaning (just like every other word in the dictionary), and since it has more than one meaning the word is ambiguous, rather than univocal, and therefore does not “univocally” refer to the office of bishop.  

If Fr. Cekada’s reasoning were correct, every sacrament would be invalid, or at least highly doubtful.  

Let’s look at the old form of episcopal consecration as one example.   Keep in mind that to be valid, the form must signify two things: 1) the Holy Ghost and 2) the office of the episcopate.   And according to Fr. Cekada, if there is any ambiguity it is invalid.  The bold parts below are supposed to signify the episcoate and the Holy Ghost

Pius XII, Sacramentum Ordinis: “Finally in the Episcopal Ordination or Consecration, the matter is the imposition of hands which is done by the Bishop consecrator. The form consists of the words of the “Preface,” of which the following are essential and therefore required for validity:  ‘Perfect in Thy priest the fullness of thy ministry and, clothing him in all the ornaments of spiritual glorification, sanctify him with the Heavenly anointing’.”

Does the phrase “fullness of thy ministry” univocally signify the office of bishop?   How many meanings do you think Fr. Cekada could unearth for the word “ministry”?    And what about “heavenly anointing”?  Who would have ever guessed that’s a reference to the Holy Ghost?

If you apply Fr. Cekada’s argument to the old form, the only conclusion an honest person can reach is that the old rite of episcopal consecration ‘is absolutely null and utterly void,’ or at least highly doubtful (and hence must be avoided).  Therefore, there must be a flaw somewhere in Fr. Cekada’ reasoning.  And indeed there is...

The flaw is a misunderstanding of what suffices for a univocal signification.  It doesn’t mean the word (i.e, “ministry”) can have only one possible meaning, or even that the word or phrase (“Heavenly anointing”) must unambiguously be understood as referring to what it signifies. All that is required for a univocal signification is that the word or phrase be accepted and used by the Church as meaning what it is intended to signify.

This brings us to Fr. Cekada’s misrepresentation of what Pius XII teaches in Sacramentum Ordinis.  Here is what he wrote:

Fr. Cekada: “Pius XII taught that a form for conferring Holy Orders must univocally (unambiguously) signify the sacramental effects: the power of the Order received (deacon, priest or bishop) and the grace of the Holy Ghost.”

That’s not what Pius XII taught.  This is what he wrote:

Pius XII, Sacramentum Ordinis: “Wherefore, after invoking the divine light, We of Our Apostolic Authority and from certain knowledge declare, and as far as may be necessary decree and provide: that the matter, and the only matter, of the Sacred Orders of the Diaconate, the Priesthood, and the Episcopacy is the imposition of hands; and that the form, and the only form, is the words which determine the application of this matter, which univocally signify the sacramental effects – namely the power of Order and the grace of the Holy Spirit – and which are accepted and used by the Church in that sense.”

The reason the words univocally signify the sacramental effect is because they “are accepted and used by the Church in that sense,” regardless of how many definitions Fr. Cekada can “unearth” for the same word or phrase.

And the phrase “spiritus principalis” has been used by the Church to refer to the office of bishops since the earliest centuries, and probably during the time of the apostles.  Do a google search of “spiritual principalis” and “ordination” or “consecration” and you will find that the form used for episcopal consecration in the most ancient rites uses the phrase spiritus principalis.  In fact, the entire form in these ancient rites is virtually identical to the "new" form used by Paul VI.  There is no doubt whatsoever that the form used in the new rite is valid.  It is more ancient and less ambiguous than the old form.  

Let's hope Fr. Cekada comes on to defend his position.  

And for the record, I didn't get my arguments from Br. Ansgar, but I did just read page four of the link you provided.   Thanks for alerting me to it, because without realizing it Fr. Cekada indirectly refutes his entire thesis.  I'll explain how later.  For now, I would suggesting saving the docuмent as a pdf, just in case it mysteriously disappear from the internet or secretly gets "revised."

It is true that the traditional names of the three orders occur in places, but, as explained at the head of this article, these names at the Reformation were often used in a sense from which all notion of the priesthood and its mystical powers had been drained off. That this was the sense in which they were intended by those who framed and authorized the Edwardine rites is proved by the statements of classical Anglican writers like Hooker, who defend the retention of the old names on the plea that "as for the people, when they hear the name [priest] it draweth no more their minds to any cogitation of sacrifice than the name of a senator or of an alderman causeth them to think upon old age, or to imagine that every one so termed must needs be ancient because years were respected in the nomination of both" (Eccles. Polity, V, lxxviii, 2). There is, moreover, the broad fact that, when the old and the new rite are compared, it appears that the difference lies just in this: that the framers of the new have cut out all that in the old gave expression to the idea of a mystic sacerdotium in the Catholic sense of the term. There is also the connected fact that the introduction of the Edwardine Ordinal was the outcome of the same general movement which led to the pulling down of the altars and the substitution of communion tables, in order that, as Ridley expressed it, "the form of a table shall more move the simple people from the superstitious opinions of the Popish mass unto the right use of the Lord's supper". - http://newadvent.com/cathen/01491a.htm "Anglican Orders"

In the beginning of Sacramentum Ordinis, Pius XII, reiterating the teaching of the Council of Trent, states: "the Church has no power over 'the substance of the Sacraments,' that is, over those things which, as is proved from the sources of divine revelation, Christ the Lord Himself established to be kept as sacramental signs." - http://www.traditionalmass.org/images/articles/NewEpConsArtPDF2.pdf, p. 12.

The reason this is important is because it demonstrates that Fr. Cekada himself realizes that it doesn’t matter if a word has multiple meanings.  What matters is the sense in which the word or phrase is “accepted and used by the Church” (as Pius XII)   Therefore, all we need to do to demonstrate what the Church means by Spiritus Principalis is quote an authority who was involved in preparing the new rite.