Judging from the Chinese structure another candidate for the First Point of Libra could be Spica (although today in the Virgo constellation), because this was their first ruling star beyond the September equinox.

Spica is obviously a word describing a point. A horn is the first point of some animals and a spike belongs in the last part of a cereal. Yet the Chinese had Spica rule their Horn.

The Chariot ought to have ended with September 22 because of number 19 - and from June 24 (Tejat Posterior) up to and including September 22 there were 91 days, a quarter of 364:

22	Well	μ Gemini (Tejat Posterior)	Tapir	(95.4)	Jun 24 (175)	175 = 165 + 10
23	Ghost	ρ Gemini ?	Goat	(112.1)	Jul 11 (192)	192 = 175 + 7
24	Willow	δ Hydrae	Stag	(129.6)	Jul 29 (210)	210 = 192 + 18
25	Star	α Hydrae (Alphard)	Horse	(142.3)	Aug 10 (222)	222 = 210 + 12
26	Extended Net	ε Hydrae / μ Hydrae	Ox	(131.9 / 157.1)	Jul 31 (212) / Aug 25 (237)	237 = 212 + 25
27	Wings	α Crateris (Alkes)	Snake	(165.6)	Sep 3 (246)	246 = 237 + 9
28	Chariot	γ Corvi (Gienah)	Worm	(185.1)	Sep 22 (265)	265 = 246 + 19
September equinox

1	Horn	α Virginis (Spica)	Crocodile	(202.7)	Oct 10 (283)	283 = 265 + 18
2	Neck	κ Virginis	Dragon	(214.8)	Oct 22 (295)	295 = 283 + 12
3	Root	α Librae (Zuben Elgenubi)	Badger	(224.2)	Oct 31 (304)	304 = 295 + 9
4	Room	π Scorpii (Vrischika)	Hare	(241.3)	Nov 17 (321)	321 = 304 + 17
5	Heart	σ Scorpii	Fox	(247.0)	Nov 23 (327)	327 = 321 + 6
6	Tail	μ Scorpii (Denebakrab)	Tiger	(254.7)	Dec 1 (335)	335 = 327 + 8
7	Winnowing Basket	γ Sagittarii (Nash)	Leopard	(273.7)	Dec 20 (354)	354 = 335 + 19
December solstice
8	South Dipper	φ Sagittarii (?)	Unicorn	(284.0)	Dec 30 (364)	364 = 354 + 10
9	Ox / Herd Boy	β Capricornii (Dabih)	Buffalo	(308.0)	Jan 23 (388)	388 = 364 + 24

Spica ruled the Horn lunar station and this name could clearly have referred to an important point (horn) in time.

(283 - 265) / 365 * 26000 = ca 1300, i.e. around the year 600 A.D. Spica would have risen with the Sun at the September equinox. At that time Sheratan no longer could indicate the March equinox and a change of ruling star should have been necessary.

In the C text I have assumed Spica should be at the great vero (with a great dot in front) and 6 lunar synodic months from the beginning of side b:
 

April 17 (107)	18	19	173	October 10 (283)	171
Cb1-1 (393)	Cb1-2	Cb1-3		Cb8-6 (569)
E tupu - ki roto		o te hau tea		vero hia
POLARIS, Baten Kaitos (26.6), Metallah (26.9), Segin, Mesarthim, ψ Phoenicis (27.2), SHERATAN, φ Phoenicis (27.4)	ι Arietis (28.0), λ Arietis (28.2)	Alrisha, χ Phoenicis (29.2)		SPICA, Alcor (202.7)
October 16	17 (290)	18		April 10 (100)
ν Centauri (208.7), μ Centauri, υ Bootis (208.8)	Muphrid (210.1), ζ Centauri (210.3)	φ Centauri (211.0), υ¹ Centauri (211.1)		Ksora (20.1)

This makes sense only if when turning the tablet around from side a to side b the reading should change from nakshatra to heliacal. When the Sun was north of the equator the nakshatra reading would south of the equator be natural and when the Sun had passed the equator the reading ought to have been heliacal.

Polaris (high up) was rising heliacally together with Sheratan (First Point of Aries) in April 17 and in October 10 Spica (First Point of Libra) was rising heliacally together with Alcor (also high up):
 

April 17	October 10
Polaris & Sheratan	Spica & Alcor
177 = 6 * 29½

With the First Point of Aries and the First Point of Libra separated by 175 nights it would have been possible to work with a year twice as long and then to add 4 extra nights in order to reach 12 * 29½ = 354.

Wikipedia was therefore hardly correct in stating that the First Point of Libra was 180º from the First Point of Aries. But in Wikipedia can only be found simple facts.

(202.7 - 27.4) / 365¼ * 360º = ca 173º.

From Spica there ought then to be another 177 days (glyphs) to the end of side b, but such is not the case:
 

October 10 (283)	168	March 28	29 (88)	30
Cb8-6 (569)		Cb14-17	Cb14-18	Cb14-19 (740)
vero hia		e noi koe te manu - kokoti hia te henua	tagata hakaitiiti	i te henua
Spica, Alcor (202.7)		no star listed	Delta (8.4)	Schedir (8.6), μ Phoenicis (8.9), ξ Phoenicis (9.0), ρ Tucanae (9.1), Deneb Kaitos, η Phoenicis (9.4)
April 10 (100)		September 26	27	28 (271)
Ksora (20.1)		Gacrux (188.7), γ Muscae (189.0), Avis Satyra (189.3), Asterion (189.5)	Kraz (189.7), α Muscae (190.2), τ Centauri (190.5)	χ Virginis (190.7), ρ Virginis (191.4), Porrima (191.5)

Perhaps the explanation was that 283 (October 10) + 171 = 454 = 100 + 12 * 29½: