2. The similarity between the words hônui and hônu makes me think there is also a common denominator in meaning between at least some of the honui glyphs and honu glyphs. Possibly the 'emblem' in form of an empty hole in the center in some way alludes to a turtle.

The 'turtle' would then in turn presumably be referring to some 'season' of the sun. The sun is a great fire in the sky and a cosmic turtle is in mythology connected with the fire in the sky. If honui glyphs mark some calendar period we should guess on a solstice - where sun moves slowly.

We have earlier (at hakatourou) seen that the Maya had a turtle at Orion (but also one at Gemini), from the broken carapace of which the Maize God rose resurrected:

... Classic-period artists depicted First Father being reborn through the cracked carapace of a turtle shell, often flanked by his two sons ...

I guess the hole in honui glyphs could refer to the hole of rebirth in the carapace of the celestial Turtle.