@he atlas itch said
"1. The four deuces, the four knights and all Wands are mapped onto Chokmah, suggesting a fiery quality to this sephira."
Yes, Chokmah is the Root of Fire. (However, in Hebraic Qabalah, it is attrributed to Water.)
"2. If you look at the overall pose of the Priestess and Emperor, they are imitating the signs for mercury and sulphur. Compare the Atus against the signs below: "
Yeah, I know you're stuck on that. Get over it. It holds up for The Emperor and The Empress, but not for Mercury, and is simply a wrong alchemical interpretation.
"3. AC's description of the Priestess is full of mercurial significance."
I can't find one. Not one. (OK, there is the sense, totally divorced from individual Trumps, in which the Middle Pillar itself might be deemed mercurial among the triad.) And there are at least a dozen explicit statements in his Book of Thoth description that are pointedly un-Mercurial.
(Every detail of the section you quote - other than the Middle Pillar = mediation idea - is decisively lunar, feminine, and non-Mercurial.)