Well i guess i might has well make a pitch then, in my view the basic utility of the hermetism would be the following, it would be an event religion more than anything, if possible it would be in it's own religious group of scholary or eseoteric religion, in wich faiths like hypistarian and other outlier faiths could be put into.There's no current plans to implement Hermeticism as a separate faith, although Harran is Platonic at start.
to go a bit more about this proposed religious group: essentially it operates similarly to how gnosticism operates in vanilla, rather then having a generic syncretism trait it has a unique "scholarly faith" tenet, that boosts learning lifestyle but make the conversion of individual characters of low learning much more difficult, other faith such has platonism and neoplatonism could also make use of this tenet, and additional effect of this tenet is that it's much cheaper to convert to faiths of this tenet if one has the scholar trait, unlike the gnostic religious who can appear has heresies of other religious, religious of this group, or any such religion with this tenet, only really appear when a character with the scholar trait reaches high stress, the specific event that encourages conversion to a different religion will always have one of these religions as a option in addition to the other the even presents.
on to hermetism it's self: for simplicities sake, hermetism in the game should be a combination hermetism the bespoque religion and hermeticism the widepsread alchemical pratice, as such it's tenet should be the esoterism, to represent the more esoteric part of hermeticsit practice, adaptive, to represent how hermetism proper can be relatively easily combined with many of the mainstream monotheist religions and either asceticism, to represent the anti-matrialist tones some hermetist philosophy had or astrology to represent it's role in hermeticist practice.
Sorry for the unprompted wall of text but i have been mulling on this one for a while, and was curious as to what where your thoughts.