The Roman calendar had half-month periods, and we can therefore reconstruct a pattern:

Beyond 5 fingers counting cannot go on. But gods have only 3 fingers. The gods above were represented as manu rere, flying beasts:

 

Ka3-1	Ka3-2 (48)	Ka3-3	Ka3-4	Ka3-5	Ka3-6	Ka3-7 (53)

Ka3-15 (3 *15 = 15) has a vertical midline. Maybe the wedge below represents full moon. It is anyhow a sign of the recycling station (henua ora).

The 2nd part of the year had months without special names, just numbers:

Yet, before September and beyond the half-month Mars was April, May, and June - another triplet of gods. I guess this was the pattern:

June should have been interrupted by summer solstice, like March by spring equinox, I think. Mercury has no place up in the sky - he is a liquid (and hardly visible anyhow).

First you counted halfmonths (fortnights) with the five fingers of your left hand (for the dark last quarter), reaching 5 * 14 = 70 (rather close to 365 / 5 = 73) nights, then there was a chaotic interregnum at spring equinox, followed by the 5 fingers of your right (sun) hand, and another interregnum for summer solstice. Perhaps.

Fire comes from above, which on Easter Island meant from the east. Everything arrived from there, fire, wind, waves. The highest end of the island was Poike.

Movement is downwards, perfectly illustrated by the rain. We call it gravitation.The first half of the year opens up the world, the second closes it down. This perpetual oscillating pattern must be mirrored in the calendar structure. Moon is lower down than Sun, and Mars comes all the way down to Earth.

The same pattern is restarted with Jupiter, followed by Venus and Saturn, the heavy old planet. Moon and Venus are midstations, variable entities. Sometimes very light, sometimes very dark.

At midsummer something more radical takes place, sun is toppled. The sky is overcast, predicting rain (a symbol for the downward movement) and the planets can no longer be seen. Maybe.

There are twice 3 light gods in the sky, Mercury is not counted. They are like the knuckles of 3-fingered hands.

In the rongorongo texts the light seasons of the 1st half of a year should be 3 in number, each though having two halves. The rest of the year was equal to 2 * 4 = 8 periods, to be counted on your own hands.

2 * 3 + 2 * 4 = 6 + 8 = 14, and 14 * 26 = 364 = 2 * 13 * 14. Between the two halves of the year there are periods which lie outside of the counting pattern. 14 * 24 = 336 (= twice 12 * 14) should be the number inside the couning patten. 364 - 336 = 28, and half of those days are located at midsummer and the other half at midwinter. It follows from the 'falling down' pattern.