Question is whether the beginning of the C text simply describes the star map or whether it also has other calendar information embedded. We should compare where the Gregorian calendar had its dates in rongorongo times on one hand with where its dates were in the times of Al Sharatain on the other:

March 21 (80)	22	23
no glyph
	Ca1-1	Ca1-2
	koia	ki te hoea
Al Fargh al Thāni-25	Uttara Bhādrapadā-27 / Wall-14	χ Pegasi (2.1), θ Andromedae (2.7)
0h (365.25)
Caph, SIRRAH (0.5), ε Phoenicis (0.8)	ALGENIB PEGASI (1.8)
Alchita, Ma Wei (183.1), Minkar (183.7), ρ Centauri (183.9)	Pálida (184.6), Megrez (184.9)	Hasta-13 / Chariot-28
		GIENAH (185.1), ε Muscae (185.2), ζ Crucis (185.4), Zaniah (185.9)

'February 23 (54)	24	25
no glyph
	Ca1-1	Ca1-2
	koia	ki te hoea
Al Fargh al Thāni-25 / Uttara Bhādrapadā-27 / Wall-14		χ Pegasi (340.4), θ Andromedae (341.0)
Caph, SIRRAH (338.8), ε Phoenicis (339.1)	ALGENIB PEGASI (340.0)
Alchita, Ma Wei (156.1), Minkar (156.7), ρ Centauri (156.9)	Pálida (157.6), Megrez (157.9)	Hasta-13 / Chariot-28
		GIENAH (158.1), ε Muscae (158.2), ζ Crucis (158.4), Zaniah (158.9)

The 'zero' day of the text could equally well refer to 0h as to the Terminalia date Februarius 23 - where 54(0) = 2 * 27(0) = 3 * 18(0). Raven was in his nakshatra (claw) position in both cases. Dates are changing with time but the stars remain firm.

Before Rangitokona raised his great star pillar the sky and earth were close together, and this should be before spring equinox:

'February 26	27	28 (59)	29	'March 1
Ca1-3	Ca1-4	Ca1-5	Ca1-6	Ca1-7
ki te henua	te rima te hau tea	haga i te mea ke	ki te henua - tagata honui	te ika
ζ Tucanae (341.7), π Tucanae (341.9)	no star listed	Ankaa, κ Phoenicis (343.2) Alphard	λ Phoenicis (344.5), β Tucanae (344.6)	no star listed
Chang Sha (159.3)	Intrometida (160.4), Acrux (160.5)	γ Com. Berenicis (161.0), σ Centauri (161.1), Algorab (161.5), Gacrux (161.7)	γ Muscae (162.0), Avis Satyra (162.3), Asterion (162.5), Kraz (162.7) Alderamin	α Muscae (163.2), τ Centauri (163.5), χ Virginis (163.7)

Therefore: one point in favour for the calendar born in the times of Al Sharatain.

Delta is at the back side of Andromeda, i.e. rather 19 days before equinox than 8 days after:

'March 2 (62)	18	equinox	7	March 29 (88)
	26 days
Ca1-8				Ca1-8
te honu				te honu
DELTA (346.6), Schedir (346.8), μ Phoenicis (347.1)				DELTA (8.4), Schedir (8.6), μ Phoenicis (8.9)
Al Áwwā'-11				Al Áwwā'-11
ρ Virginis (164.4), PORRIMA, γ Centauri (164.5)				ρ Virginis (191.4), PORRIMA, γ Centauri (191.5)

The last star of Andromeda is Alamak (γ at her Achilles point) and at her midline is Mirach (β). Therefore should η be before 0h:

March 30	31	April 1 (91)	2
Ca1-9	Ca1-10	Ca1-11	Ca1-12
te manu te henua		te Rei	kua hakagana
ξ Phoenicis (9.0), ρ Tucanae (9.1), Deneb Kaitos, η Phoenicis (9.4)	Achird (10.7)	Legs-15	Cih, λ Tucanae (12.4)
		ρ Phoenicis (11.2), η ANDROMEDAE (11.4)
ι Crucis (192.2), β Muscae (192.5), Mimosa (192.9)	no star listed (193)	κ Crucis (194.4), ψ Virginis (194.5), μ Crucis, λ Crucis (194.6), Alioth (194.8)	Minelauva (195.1), Cor Caroli (195.3)

'March 3	4	5 (65)	6
Ca1-9	Ca1-10	Ca1-11	Ca1-12
te manu te henua		te Rei	kua hakagana
ξ Phoenicis (347.2), ρ Tucanae (347.3), Deneb Kaitos, η Phoenicis (347.6)	Achird (348.9)	Legs-15	23h (350.0)
		ρ Phoenicis (349.4), η ANDROMEDAE (349.6)	Cih, λ Tucanae (350.6)
ι Crucis (165.2), β Muscae (165.5), Mimosa (165.9)	no star listed	11h (167.4)	Minelauva (168.1), Cor Caroli (168.3)
		κ Crucis (167.4), ψ Virginis (167.5), μ Crucis, λ Crucis (167.6), Alioth (167.8)

The nakshatra position 193 + 1 at April 1 could motivate the Rei glyph, but at least as possible is nakshatra 11h at Ca1-11 ('the first pair of 11h').

But I am already convinced - when applying Gregorian dates I should use the times of Al Sharatain, not the time of rongorongo. At least when reading the beginning of side a.

By the way, it strikes me that Andromeda has her head at the inundated earth of the Pegasus Square and her 'tail' at the 'ittle lion' in the dry desert.