Yeah but the creator of the project can suggest whatever they want if they don't understand the license they use.

Going over CC-BY-SA for those used to software licenses only: If I make a work which uses CC-BY-SA material I have to provide attribution. If I modify the emoji to suit my own purposes, I need to release these new emoji under CC-BY-SA, and attribution to the originals must be provided, they may not be kept proprietary.

Using it in a project is redistribution, modifying it is adaption.