I searched for kohio in Churchill and found evidence for the penis being regarded as similar to bamboo:

 

Kohi Pau.: 1. To glean. Mgv.: kohi, to gather, to collect. Ta.: ohi, to glean. Mq.: kohi, id. Ma.: kohi, to gather. 2. Bamboo. Mgv.: kohe, id. Ta.: ohe, id. Mq.: kohe, id. Sa.: 'ofe, id. Ma.: kohe, a plant name. 3. Diarrhea. Ta.: ohi, dysentery. Churchill. Mgv.: kohiko, a small bag mounted in the fruit-picking fork. Mq.: kohiko, a small net. Churchill.

Kohe A plant (genus Filicinea) that grows on the coast. Vanaga. Vave kai kohe, inaccessible. Churchill. *Kofe is the name for bamboo on most Polynesian islands, but today on Easter Island kohe is the name of a fern that grows near the beach. Barthel 2.

In the Paumotuan dialect kohe has been twisted into kohi.

Kohiko is used when picking fruits with a fork. I immediately think about toa and tao:

 

The sign of Y may be the fork used when picking the fruits in the 2nd half of the year.

Whatever the exact meaning of tao, it is a sign of the 1st half of the year, like a seed sailing on the sea, carrying the 'fire' of life inside. The slightly different design used in the text of G in the 2nd half of the year should represent the other end of the cycle, the time when the 'fruits' should be gathered.

 

Ga1-25	Gb1-24

If Ga1-25 is like a seed to be planted in mother earth, then Gb1-24 is the 'fruit' of the operation, carrying nourishment. It could function as a new seed, or it will be eaten.

The small bag will 'eat' the 'berries'. It is not the small male 'bag' with seeds, but a female bag for collecting.

The forked stick (toa) is dry and can be used to build a new fire after the picking season is over. Or it can be used for digging in the earth.

We should not forget tau papa (which Barthel translated as 'raft' with a question mark). It is just a small vocal change from tao to tau. Perhaps tau papa basically means the season of flatness (i.e. solstice). In connection with a broken neck there should be a sea journey, and a flat raft on the flat surface of the sea is indeed one possibility for 'fire' to survive:

... ka hati toou ngao e oto uta e te ariki e / mo tau papa rangaranga o haho i te tai / mo tuu huehue rangaranga o haho i te tai / mo tau hahave rere ai ka pae / mo tae ngu rere ai ka pae / mo te ika aringa riva nei he aku renga ai ka pae

Broken is your neck, oh Oto Uta, oh king! / Floating (?) like a raft (?) out at sea. / To be erected for the drifting huehue (fish) out at sea. / Able (?) to put an end to the flight of the flying fish hahave; / Able (?) to put and end to the flight of the flying fish ngu; / Put an end to this fish, a dorado, with the good face! (E:87-90) ...

 

Papa 1. Underground rock; motionless; rocky sea bottom; large flat stone; figuratively: tagata papa important man, author of great works. 2. Wooden plank currently used much like a surf-board in the sport called garu; it was formerly called papa gaatu mo te garu, because it was made from dry totora leaves woven into the shape of a plank. 3. To line up things side by side on a flat surface, for instance, to line up fish on top of a flat stone. Vanaga. Shoulderblade. Papapapa, a chill, to shiver, to tremble, to shudder. Churchill.

A wooden plank (papa) was once used as a surf-board in a sport called garu - earlier called papa gaatu mo te garu 'because it was made from dry totora leaves woven into the shape of a plank'.

To translate tau papa rangaranga o haho i te tai we also need to be aware of the possible meanings of ragaraga and haho:

 

Raga 1. To run together, forming small lakes (of rainwater) ku-raga-á te vai. 2. Fugitive (in times of war or persecution); to take refuge elsewhere; to move house; homeless; poki poreko raga, child born while its parents were fugitives. 3. Said of fish swarming on the surface of the sea: he-raga te îka, ku-mea-á te moté, te nanue para..., you can see many fish, fish are swarming, mote, nanue para, etc. Ragaraga: 1. To float on the surface of the sea: miro ragaraga i ruga i te vai kava, driftwood floating on the sea. 2. To move ceaselessly (of people), to pace back and forth (te eve o te tagata); to be restless: e-ragaraga-nó-á te eve o te tagata, the man is nervous, worried, he paces back and forth. 3. E-ragaraga-nó-á te mana'u is said of inconstant, fickle people, who cannot concentrate on one thing: e-ragaraga-nó-á te mana'u o te ga poki; ta'e pahé tagata hônui, ku-noho-á te mana'u ki ruga ki te aga, children are fickle; they are not like serious adults who concentrate their work. Vanaga. 1. Captive, slave, to take captive; hakaraga, to enslave. Mq.: áka, conquered. 2. To banish, to expel, to desert; ragaraga, to send away, to expel; hakaraga, to banish, to drive off. Mq.: áka, wanderer, vagabond. Ragaraga, to float, to fluctuate; eve ragaraga, ennui, to weary. T Mgv.: raga, to swim or float on the surface of the water. Mq.: ána, áka, to float. Churchill. Sa.: langa, to raise, to rise. To.: langa, to raise up the soil; fakalanga, to raise up. Uvea, Fu.: langa, to raise. Niuē: langa, to rise against; langaaki, to raise up. Nukuoro: langa, to float. Ha.: lana, id. Ma.: ranga, to raise, to cast up. Mgv.: ranga, to float on the surface of water. Pau.: fakaranga, to raise, to lift up. Ta.: toraaraa, to raise up. Mq.: aka, ana, to swim on the surface. Vi.: langa, to be lifted up, said of a brandished club ... Churchill 2.

Haho Outside. Vanaga. Hahoa (ha causative, hoa) to cut, to wound, to hurt. PS Mgv.: tahoa, to make papyrus by beating. Sa.: foa, to chip, to break. To.: foa, to crack, to make an opening. Fu.: foa, to dig, the rent in a mat. Underlying the Nuclear Polynesian significations the primal sense seems to be that of a hole. The Rapanui, a causative, is a clear derivative in the cutting sense; wound and hurt are secondary withing this language. The Mangarevan composite means 'to beat until holes appear', which is a distinctive character of the beaten bast of the paper mulberry in the condition in which it is ready for employment in making tapa. Churchill.

Beating tapa is the work of women. Why did I think so? Because tapa is beaten into white flatness and because I thought about the meaning of papa. Flat stones (papa) and flat cloth (from wood), tapa, are similar.

... The chief thus makes his appearance at Lakeba from the sea, as a stranger to the land. Disembarking at the capital village of Tubou, he is led first to the chiefly house (vale levu) and next day to the central ceremonial ground (raaraa) of the island. 

At both stages of this progression, the pretender is led along a path of barkcloth by local chieftains of the land. In Lau, this barkcloth is prescriptively a type considered foreign by origin, Tongan barkcloth. Later, at the kava ceremony constituting the main ritual of investiture, a native chieftain will bind a piece of white Fijian tapa about the paramount's arm. 

The sequence of barkcloths, together with the sequence of movements to the central ceremonial ground, recapitulate the correlated legendary passages of Tui Nayau from foreign to domestic, sea to land, and periphery to center. The Fijian barkcloth that in the end captures the chief represents his capture of the land: upon installation, he is said to hold the 'barkcloth of the land' (masi ni vanua). 

The barkcloth thus has deeper significance. In general ritual usage, barkcloth serves as 'the path of the god'. Hanging from the rafters at the rear, sacred end of the ancient temple, it is the avenue by which the god descends to enter the priest ...

The name of the central ceremonial ground of the island, raaraa, explains the meaning of the midnight henua:

 

 

Ga Preposed plural marker of rare usage. 1. Sometimes used with a few nouns denoting human beings, more often omitted. Te ga vî'e, te ga poki, the women and the children. Ga rauhiva twins. 2. Used with some proper names. Ga Vaka, Alpha and Beta Centauri (lit. Canoes). Vanaga.

Gaa Gaaha, to burst, to become ruptured, to have a discharge of pus, of blood. Ku gaaha te toto o te ihu. He had a nose-bleed. E û'i koe o gaaha te îpu. Be careful not to break the bottle (lit. look out lest the bottle burst). E tiaki á au mo gaaha mai o te harakea. I shall wait for the abcess to burst. Gaatu, totora reed. Vanaga. To break, to split, to crack, to rive; fracture, fissure, break, crack, crevice (gaaha); niho gaa, toothache, broken teeth; gaamiro (miro, ship) shipwreck; gaàpu (pu 2), abortion; poki gaàpu, abortive child. T Mq.: naha, nafa, split, fissure. Ta.: aha, afa, crack fissure. Gaatu 1. Bulrush, reed. 2. (gatu).  Churchill.

The 'reed' is the last of the 'trees':

... what is surprising indeed was the manner of Quetzalcoatl's actual return. The priests and astrologers did not know in what cycle he was to reappear; however, the name of the year within the cycle had been predicted, of old, by Quetzalcoatl himself. Its sign was 'One Reed' (Ce Acatl), which, in the Mexican calendar, is a year that occurs only once in every cycle of fifty-two. But the year when Cortes arrived, with his company of fair-faced companions and his standard, the cross, was precisely the year 'One Reed'. The myth of the dead and resurrected god had circumnavigated the globe ...

... Via The White Goddess we have now received one more piece to this puzzle: 'The number twelve has the sense of established power, confirmed by the Irish use of reeds in thatching: a house is not an established house until the roof is on. The month extends from October 28th to November 24th.'...

Reeds are used not only for floating on top of the sea but also on top of houses. They belong to the highest position. The highest position is reached at the end of the path, therefore it signifies the last of the seasons.

... Totora reed mats were used to enwrap their precious objects (such as rongorongo boards). Reeds were used to preserve 'life' - as when mummies were enwrapped in mats. The Maya and Aztec indians 20-day calendar had reed (Ben / Aj respectively Acatl) as number 13.

That grass is immediately preceding and jaguar (the big head-crushing night cat) immediately following seems as it should be ...

Grass characterizes the uri season, then comes the water and reed is the proper 'tree' to keep dry, to sit on.