Are the antecedents of the different thee/Thee, in the English translation of Suriy-i-Haykal, different? This may seem a minor question, but if it is intentional, which I would guess it is, there must be a more profound reason for it.
1. The translation of the Universal House of Justice is most faithful and that one should not interpret the thee and Thee as theological as essentially all refer to the One. BUT the small thee is used for example about the lisán [tongue of this Temple]:
21 O Tongue of this Temple! We, verily, have created thee through Our name, the All-Merciful, have taught thee whatsoever had remained concealed in the Bayán, and have bestowed upon thee the power of utterance, that thou mayest make mention of Mine exalted Self amidst My creatures. Proclaim, then, this wondrous and mighty Remembrance, and fear not the manifestations of the Evil One. Thou wert called into being for this very purpose by virtue of My transcendent and all-compelling command. Through thee have We unloosed the Tongue of Utterance to expound . . .2. The small thee is also used for a letter of the Haykal. For example: the third letter [káf] or the fourth letter [lám]:
39 O Third Letter of this Temple, betokening My name, the All-Bountiful! We have made thee the dawning-place of Our bounty amidst Our creatures . . .and again
46 O Fourth Letter of this Temple, betokening the attribute of Grace! We have made thee the manifestation of grace betwixt earth and heaven. From thee have We generated all grace in the contingent world, and unto thee shall We cause it to return. And from thee shall We manifest it again, through a word of Our command. Potent am I to accomplish whatsoever I desire through My word "Be", and it is!3. When the WHOLE TEMPLE is intended capital T is used, "Thee":
63 O Temple of Holiness! We, verily, have cleansed Thy breast from the whisperings of the people and sanctified it from earthly allusions, that the light of My beauty may appear therein and be reflected in the mirrors of all the worlds. Thus have We singled Thee out above all that hath been created in the heavens and the earth, and above all that hath been decreed in the realms of revelation and creation, and chosen Thee . . .4. Therefore, a small 't' as in 'thee' is used for the parts (ajzá) of Haykal and a capital 'T' as in 'Thee' for the Whole of Haykal:
72 O Living Temple! We have made Thee the Dayspring of each one of Our most excellent titles, the Dawning-Place of each one of Our most august attributes, and the Fountainhead of each one of Our manifold virtues unto the denizens of earth and heaven. Thereafter have We raised Thee up in Our own image betwixt the heavens and the earth, and ordained Thee to be the sign of Our glory unto all who are in the realms of revelation and creation, that My servants may follow in Thy footsteps, and be of them who are guided aright. We have appointed Thee the Tree of grace and bounty unto the dwellers of both the heavens and the earth. Well is it with them who seek the shelter of Thy shade and who draw nigh unto Thy Self, the omnipotent Protector of the worlds.