By unhinging the leap day from its proper place between Castor and Pollux the door was left open for other 'improvements'. The old 'Gate in Gemini' through which spirits could come and go had been closed.

My picture above illustrates at top center Orion and below the central hollow between the Twins. At the bottom of this hole α (Castor) is at left and Pollux (β) at right. The 'door' between one side and the other, at Procyon (α Canis Minoris), has evidently been uplifted and moved to the right.

The view is from south of the equator and looking towards the rising stars in the east. Maybe the explorers of the Middle Ages had become aware of how the sky looked 'down under' and perhaps the following discussions lead to moving the 'terminalia' 5 days ahead, from February 23 to February 28.

How could order be restored? Perhaps those who on Easter Island still saw the movement of spirits as a necessary ingredient in the cosmic order developed a year with 368 days, beginning at January 3. As a consequence their 'February 23' would arrive 2 days later than if the year had begun with January 1.

In C the structure indicates the leap day 'door' could have been moved to the end of the extraordinary long manzil Saad Al Thabib, where a pair of 'coconut trees' (niu) could be illustrating the change from below (before) to above (after):

Saad Al Thabib 11	12	13
February 21	22 (53)	23 (Terminalia)
Ca12-21	Ca12-22	Ca12-23 (339)
te niu ku hakatu ua	te maitaki - kupega tuku hia mai	mata hakatuu
λ Piscis Austrini (336.8), ε Cephei (337.2), Ancha (337.4)	ρ Aquarii (338.2)	Sadachbia (338.6), π Aquarii (339.5)
		Castor (419)
August 23	24 (236)	25
An Nathra 7	8	9 (101)
Simiram, Adhafera, Tania Borealis (154.7), Algieba, q Carinae (155.5)	Tania Australis (156.0)	μ Hydrae (157.1)

14	15 (285)		Saad Balaa 1	2
24 (Bissextum)	25 (421)		26 (422)	27 (58)
Ca12-24	Ca12-25		Ca12-26	Ca12-27
te vae paupau	te niu tutuu		oho te rima o te niu	a hagahaga
ρ Cephei (340.2), ζ Aquarii (340.4), Alrediph (340.5)	σ Aquarii (340.9), Homan, β Piscis Austrini (341.2)		υ Aquarii (341.9), η Aquarii (342.1)	Situla (342.7), ε Piscis Austrini (343.5)
Procyon (420)	Pollux (421)		Azmidiske (422)
26	27		August 28 (240)	29
10	11		An Nathra 12	13 (105)
no star listed	Shir (158.9), p Carinae (159.3)		φ Hydrae (160.3)	no star listed

Azmidiske is ξ Puppis and the little 'dog' - ρ - at the stern of Argo Navis (where the rudder should be) has Azmidiske at his back side, κ (Markab Puppis) in the center, and some for me unknown star in front:

Canis Major is at left and instead of a gap between Castor and Pollux we can imagine a gap between the Vela part and the Carina part. The ruling part, where the Ship has her pilot must be Canopus (α Carinae).

Looking for ρ Puppis in my star list I cannot find it. Looking again in Wikipedia it is easy to find it and its name there is Tureis. But in my star list Tureis is the name for ι Carinae, in Hevelius' picture where the 'double wedge' is forcing itself into the Tree.