Does this mean that the same glyph (moon concave to the right) should be read in 30 different ways depending on where it is positioned in the calendar?

Will we not be able to allocate specific 'readings' to the glyphs of rongorongo without referring to the surronding glyphs?

I suggest that what you read, whether rongorongo miroglyphs or the English language as it is used in ordinary books, always can be understood only through the reader's creative processes.

These creative processes integrate the surrounding written glyphs / words to a coherent whole. And necessarily the implied meanings must be recreated by the reader according to the 'maps' which are more or less common in the culture which is using the language.

There are, though, a few poor people who can read texts aloud quite correct, but without having any idea whatsoever about the meaning of the text. Ordinary people experience the same feeling when reading e.g. the forms used for income taxes.