In all parts. The center is has the biggest text. If it helps think of it this way: you're looking through a black fence at something colorful on the other side.
Edit: You're right, the text is only in the middle and next largest "fold." The rest is, spoiler, alien face glyphs.
Confirmed! The letters are easy to read once you know where to look.
Indeed the regular pattern can be seen as alien faces. But they are so close by that to me the slanted "eyes" and the cup-like "chins" more readily form plant shapes, with pairs of "leaves" and "flowers" above them instead.
Edit: You're right, the text is only in the middle and next largest "fold." The rest is, spoiler, alien face glyphs.