But March 1 was the first day before the Kalends of March:

... The leap day was introduced as part of the Julian reform. The day following the Terminalia (February 23) was doubled, forming the 'bis sextum - literally 'double sixth', since February 24 was 'the sixth day before the Kalends of March' using Roman inclusive counting (March 1 was the 'first day').

Below I have therefore adjusted my earlier number for days in the month Martius from 31 to 30, which leads to day number 320 at the extraordinary Cb13-10 (where we according to Metoro should count) because 297 (Martius - Sextilis) + 23 (Ianiarius 1-23) = 320:

306	'January 21	22	23	24
	'Ianuarius 21	22	23 (320)	24
	February 17	18	19 (50)	20
	Februarius 17	18	19	20
	Cb13-8	Cb13-9 (700)	Cb13-10	Cb13-11
	te moa	kua vero	te mamahia	te vero
	η Piscis Austrini (333.4)	Rooftop-12	ι Pegasi (335.0), Alnair (335.1), μ Piscis Austrini, υ Piscis Austrini (335.3), Woo (335.7), Baham, τ Piscis Austrini (335.8)	ζ Cephei (336.2), λ Cephei (336.3), -/270 Lac. (336.7), λ Piscis Austrini (336.8)
		22h (334.8)
		Kae Uh (334.0), Al Kurhah (334.4), SADALMELIK (334.6), ι Aquarii, ν Pegasi (334.7)

I have simplified above and not tried to show also the nakshatra dates. But, as we should remember, the other King Star (Regulus) was at RA day 152.7 = calendar day 80 + 152 = 232 (August 20), and 232 - 183 = 49 (February 18) was its nakshatra date. The distance between them did not change over time, it was in principle eternal, whereas 22h was dependent on where the March equinox for the moment was among the stars.

We can guess the creator of the C text had arranged it so that this important cardinal point - where one King was reflected by the other - was at glyph 700. But to be more exact Sadalmelik should be located a little later than at 334.6 in order to be precisely at the other side of the sky compared to Regulus. 152.7 + 365¼ / 2 = 335.3, i.e. at Cb13-10.

Regulus	182	Sadalmelik	183
152.7		334.6

Let's now complete our review of the last part of side b:

'January 25	26	27
'Ianuarius 25	26	27 (324)
February 21	22	23 (54)
Februarius 21	22	23 (Terminalia)
Cb13-12	Cb13-13	Cb13-14
te ariki	te vage Rei	te hokohuki i te inoino
ε Cephei (337.2),  1/325 Lac. (337.3), Ancha (337.4), α Tucanae (337.9)	Al Sa'ad al Ahbiyah-23 / Shatabisha-25	β/172 Lac. (339.2), 4/1100 Lac. (339.4), π Aquarii (339.5)
	ρ Aquarii (338.2), 2/365 Lac. (338.5), SADACHBIA (338.6)

'January 28	29	30
'Ianuarius 28	29 (326)	'Februarius 1
BISSEXTUM (6)		5
Februarius 24	Februarius 24	25 (56)
δ Tucanae (340.1), ρ Cephei (340.2), ζ Aquarii (340.4), Alrediph (340.5), 5/1100 Lac (340.7), σ Aquarii, 6/650 Lac. (340.9)	Leap night	α/91 Lac. (341.1), Homan, β Piscis Austrini (341.2), ν Tucanae (341.5), υ Aquarii (341.9)
February 24	25 (56)	26
Cb13-15 (314)	Cb13-16	Cb13-17 (708)
kua moe ki te marama	e marama erua	te kava - te moa
δ Tucanae (340.1), ρ Cephei (340.2), ζ Aquarii (340.4), Alrediph (340.5), 5/1100 Lac (340.7), σ Aquarii, 6/650 Lac. (340.9)	α/91 Lac. (341.1), Homan, β Piscis Austrini (341.2), ν Tucanae (341.5), υ Aquarii (341.9)	η Aquarii (342.1), Situla (342.7)

'January 31	'February 1	2 (33)	3 (400)	28
'Februarius 2	3	4 (330)	5
4	3	2	1
Februarius 26	27	28 (60)	Martius 1 (60)
η Aquarii (342.1), Situla (342.7)	ε Piscis Austrini (343.5), ο Pegasi (343.8)	Matar (344.2)	λ Pegasi (345.0), ξ Pegasi (345.1), τ Aquarii (345.7), μ Pegasi (345.9)
February 27	28 (59)	29 (425)	March 1 (60)
Cb13-18	Cb13-19	Cb13-20	Cb13-21 (320)
ihe tara tu	te hokohuki	te henua	te hokohuki hoi haatu ia - te hokohuki
ε Piscis Austrini (343.5), ο Pegasi (343.8)	Matar (344.2)	Leap night	λ Pegasi (345.0), ξ Pegasi (345.1), τ Aquarii (345.7), μ Pegasi (345.9)

I find these results quite encouraging. Although disturbingly complicated.

In rongorongo times March 1 (60) would have been at glyph 320 counted from Cb1-1, and at Cb13-21 we could count 13 * 21 = 273 (= 3 * 91), alluding to the last day of September and the end of the winter half of the year on Easter Island.

The 'Octopus tentacles' could have measured 40 days (320 / 8 = 40) and in the times of Al Sharatain Cb13-21 was at day 400 counted from 0h in the previous year. 'February 3 = 34 + 366 = 400. But according to the old Roman calendar this was 'Februarius 5 (331), because 355 - 331 = 24 days remained of the year. 'Februarius 5 + 24 Þ 23 days to 'Februarius 28 + 'Martius 1.

11 days earlier, at day 320, was 'Ianiarius 23, precisely half a year later than heliacal Regulus.

Glyph 314 counted from Cb1-1 is Cb13-15 where in rongorongo times Bissextum would have begun, if the Julian leap day system had been used.

Side b could have had 'March 1 as its last glyph because this was the situation in the times of Al Sharatain (if not the old Roman calendar was used). At that time the Sun would have been at Delta:

'March 1		Delta	δ Andromedae	8.4	March 29 (88)	-	-
0	-	Zero	η Andromedae	11.4	April 1 (91)	-	0
1	Al Sharatain	Pair of Signs	β Arietis (Sheratan), γ (Mesarthim)	27.4	April 17 (107)	16	16
		Musca Borealis	35 (Head of the Fly), 39 (Kaffaljidhma), and 41 Arietis (Bharani)	41.4	May 1 (121)	14	30
2	Al Dabarān	Follower	α Tauri (Aldebaran), θ¹, θ²´, γ (Hyadum I), δ (Hyadum II), ε (Ain)	63.4	May 23 (143)	22	52

Alamak (γ), which in rongorongo times was at 29.7 would have been Andromeda's last star also in the times of Al Sharatain. It would have risen with the Sun only a pair of days after 0h.

29.7 - 27 + 183 = 185.7 = 265.7 - 80, which means Alamak would have been close to the Full Moon in September 22 (265). Stars should be watched in the night, not when they are close to the Sun.