Can I be honest. I don't think "Guizhong is dead and her death is important to Ping's character development" is a good reason for her to not be playable, not only because Zibai was also dead, but because Ping has already undergone character development beyond Guizhong for 6 years
The 3.4 Lantern Rite in particular was quite literally /about/ Ping (and Cloud Retainer) processing their grief over Guizhong, and moving on. Her playing her guzheng during the orchestral performance was symbolic of her moving on from Guizhong's death!!
Lisa's is a little different, as hers is an octagram. Hroptatyr's spell is a heptagram, which is nearly identical to the ones manifested by the Hypostases. It's infamously used by the esoteric cult of Thelema (the primary basis for the Narzissenkreuz) in their Seal of Babalon
Okay, enough time has passed
Can we address the elephant in the room????
This is Hroptatyr’s spell of the blessing/curse of Immortality in the cutscene… and well, Lisa’s charged attack.
The heptagram in alchemy also represents the 7 Classical Planets (Sun, Moon, Mars, Venus, Mercury, Jupiter, Saturn), and is a common symbol overall in Kabbalah.
For anyone that genuinely believes Zibai was pulled out of thin air by the writers, it is sorely underappreciated how she was the single missing piece for /a lot/ of Liyue's lore that has been established since 1.0.
The Solar Chariot, the Lunar Carriage, and why they are one and the same —
An exploration of Zibai's place among the Morning Stars, what she tells us about Teyvat's cosmological beliefs, and Liyue's history. 🧵
mentioned in 1.0 (book and guesthouse's name), and then in 5.2, 5.3, and luna i. the entire chasm was released in 2.6 along with the mention of her fallen chariot, and her people migrated to chenyu vale (released in 4.4) and upheld rituals that involved celadon wares