Waite's paper "The Tarot and the Rosy Cross" was undated but speculation is it's from c. 1910 [Darcy Kuntz], before he started writing FRC rituals. There's a link here to a PDF
http://tarothermeneutics.com/classes/waite-trinick/Week2.html, see "The article entitled 'The Tarot and the Rosy Cross' from 1910." It reproduces Waite's paper and includes a footnote that say it's "Independent and Rectified Rite typescript" which would presumably place it during the IRR period.
The placement of Temperance and the Lovers has been a problem for me. I've gone by the information in the rituals I'm in possession of. I'll explain how I reached the conclusions I did.
Temperance is shown and explained to the candidate in the advancement from Practicus (Hod) to Philosophus (Netzach) on the 27th path. To show that the 27th path is indeed Hod-Netzach: "The path by which you have traveled is that from which you will enter the holy Sephira Netzach in the Second Point of the Grade. It is called the 27th path and also the active intelligence, a spirit that informs all things and is the motion thereof." Here's the description of the Great Symbol of the 27th path from the Philosophus initiation. Some of the language does sound like it could easily belong on path 26:
"The symbol that lies uppermost on the Altar is that of the 27th path. It represents Shekinah as the Lady of Reconciliation and Lady of the Pillar of Benignity, intermingling and reconciling the influences of Chesed and Geburah, regarded as cleansing water and saving fire. They are poured forth from two Chalices, which have a meeting point at Yesod and descend thence as a river of life in Malkuth. In the ascent of the Tree this symbol signifies the will toward rebirth, being the last mystery unfolded by the Grades of the Rosy Cross at that point where the world of formation merges in the world that is beyond. In the descent of the influences from above it signifies the virtues and graces of the Pillars on the right and the left uniting with those that come down from the Middle Pillar, represented by Shekinah, who is herself the vesture of Messias. Her Chalice is a Chalice of salvation, a principle of sacramental life. Her Cup is the Cup of benedictions. It is an eternal Cup of mercy, uplifted in the worlds of the Tree. It is also a well of cleansing, even as the laver of Moses, and a deep water of illumination, like the sea of Solomon."
Waite describes her as "Lady of the Pillar of Benignity" which definitely sounds like she should be on the central pillar, but she's shown to the candidate on path 27. It seems possible in this case her function is different from her actual placement on the paths. I made an illustration once upon a time in which I tried to picture how this might look. Her feet are standing on path 27th and she's reaching up to Geburah and Chesed.
http://s3.postimg.org/3twttwa5v/Untitled_1.jpg
Then there's Marriage (the Lovers). It's shown to the candidate in the Portal ritual from Yesod to Tiphareth on the 26th path. This couldn't really be anything other than the Lovers:
"Beneath the Banner of the Middle Path is a symbol representing marriage. You were told in the 4 = 7 Grade [Philosophus] that Shekinah is the feminine and Messias is the male aspect of the Divine in manifestation. The union of both must be attained in us, and it is this which you see before you, the wedlock of the soul and the Christ natures, under the wings of Shekinah. The ascent into Union by way of the Middle Pillar is the path to your own marriage. At the beginning it is like the upward breathing of a pure spirit, and the breath of the Spirit comes down. And till the great day of consummation the Spirit and the bride say, Come. The benign and gracious being who officiates at the Espousals before you is also a symbol of the Second Birth in spiritual consciousness. She presides over marriages and births. He who has attained to this state of regeneration in God shall draw, my Brother, all parts of his personality into the redemption of the higher nature. He shall raise up his fallen Sephiroth, including Malkuth."
In this description Waite doesn't specifically say it's the 26th path, only that it's the "middle path." Elsewhere in the ritual it's made clear that Yesod-Tiphareth is path 26. "The Great Symbols of the Paths, displayed beneath their Banners, reveal to you that in the nature of things there was no other path of
ascent open than that which you have followed, namely, the 26th Path." Note the word "ascent." The 26th path is vertical. And, "You stand now symbolically on the threshold of the 26th Path." This said to the candidate as he/she is in Yesod preparing to ascend.
If you check the roman numerals at the bottoms of the Trinick Temperance and Lovers, which indicate their paths, the Lovers is 26 and Temperance is 27.
As for Unitas, this is found in the Philosophus initiation:
"But we have told you already that Shekinah in our mystical allegory is the proclamator of unity and the guide of man therein. As the He final in Malkuth, she is in the state of separation or exile, and so also is the soul of man, apart from the Spouse of the soul. In the state of Union, which is the state of the Middle Pillar above Malkuth [Yesod], the He is in union with the Vau, as exhibited by the diagram before you and as represented, also traditionally, in Rabbinical Hebrew by the exclamation Vah, which expresses a state of joy. But this union, which begins in Yesod and is so symbolized therein, is perfected in Tiphereth, where the Lover and Beloved are no longer face to face, in simple union no longer, but in the condition that is called UNITAS, wherein there is no passage between subject and object, for all things that belong to love have been made one in the heart of love.
This describes progressively higher states of union on the middle pillar. That of Tiphareth Waite has designated UNITAS. The Priest, in the Great Symbol for Daath, has UNITAS written on his mitre, but apparently this is a reference to Tiphareth. Again, this is based on the rituals I have. The authors of
Abiding in the Sanctuary may be privy to other information.