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It just means that they cannot take a second move action.
Harmonize may not target Mana Crystal and Mana Flowers. The target line says object. The card text sets the limitation that the object must have the channeling trait. Neither Mana Crystal or Mana Flowers have a channeling trait. They grant a channeling bonus to their controller
Edit: I originally answered yes to the Harmonize and this was incorrect. I changed the post too the correct answer. Sorry for any confusion I caused.
I used to think I can use Harmonize on Mana Crystal and Mana Flower too before. When I started the game. Since then I look at the purple hand symbol for me to use it.
From Codex:
Object definition: Enchantments, Equipment, Creatures and Conjurations (Mana Crystal and Mana Flower belongs here) are spells which become objects in the game, remaining in play after they are cast.
Channeling: Some object have a channeling attribute which is how much mana they collect each round during the channeling phase
Channeling +/- X: Modifies a creatures channeling attribute by +/- X. Channeling cannot reduce below 0. Modifies only existing Channeling. It has no effect on Object (see definition above) without a Channeling attribute.
From the above, I guess where the confusion is. The Mana Crystal does not have the symbol of channeling though and this is why you can't add it.